Code Review for Product Managers: What You Should Know

By Priya Shankar, Head of Product at Glue

If you have ever waited on a feature that was "done" but stuck in review for days, you already know the code review process product manager involvement can help untangle. Code review is one of those engineering rituals that directly shapes your roadmap, your timelines, and your team's velocity. Yet most PMs treat it like a black box. That is a mistake.

I have spent years sitting between engineering and product, and I can tell you: understanding code review does not mean you need to read code. It means you need to understand what is happening, why it matters, and what questions to ask when things slow down.

This post will walk you through the code review process from a PM's perspective, so you can have better conversations with your engineering team and make smarter planning decisions.

Let me be honest. You do not need to approve pull requests. You do not need to learn Git. But you absolutely need to understand how code review affects the work your team ships.

Code review is where quality happens. It is where one engineer looks at another engineer's changes and checks for bugs, readability, performance issues, and alignment with the broader system. Think of it as the editorial process for code. A writer submits a draft; an editor reviews it before it goes to print.

When code review works well, fewer bugs reach production. Knowledge spreads across the team. Junior engineers learn faster. The codebase stays consistent and maintainable.

When it breaks down, everything slows. Features pile up in review queues. Engineers context-switch between writing new code and reviewing old code. Small changes sit untouched for days because the one person who understands that part of the system is overloaded.

As a PM, code review health is a leading indicator of delivery speed. If your team's review cycle time is creeping up, you will feel it in your sprint velocity long before anyone flags it in standup.

According to a study by SmartBear, code reviews that examine more than 400 lines of code at once see a significant drop in defect detection. That means how your team structures its work, including PR size, directly affects the quality of what ships.

Here is the simplified version of what actually takes place during a code review.

An engineer finishes a piece of work and opens a pull request (PR). This is a proposal to merge their changes into the main codebase. The PR includes the code changes, a description of what was done and why, and often links to the ticket or spec.

One or more teammates then review the PR. They read through the changes, leave comments, ask questions, and suggest improvements. Sometimes they request changes before approving. Sometimes the review sparks a broader discussion about system design.

Once the PR is approved, the code gets merged and (depending on your deployment process) shipped to users.

What PMs often miss is that review is not just a gate. It is a conversation. The back-and-forth in a PR often surfaces architectural decisions, trade-offs, and scope questions that should loop back to product. If an engineer discovers during review that a feature implementation will create performance issues at scale, that is product-relevant information.

This is one reason why building trust between PMs and engineers matters so much. When there is trust, engineers flag these issues early instead of quietly working around them.

This is the part that keeps PMs up at night. You scoped the feature. Engineering estimated it. The code is written. And then it sits in review for three days.

Code review time is one of the most common sources of "invisible" delay in product development. It does not show up in your estimates because engineers typically estimate the time to write the code, not the time to get it reviewed and merged.

Here are the timeline impacts you should watch for:

Review queue depth. If your team has a dozen open PRs at any given time, new submissions go to the back of the line. This is a capacity problem, not a laziness problem.

Reviewer availability. Some parts of the codebase need review from specific people. If that person is on vacation, in meetings all day, or working on their own feature, reviews wait. Understanding software architecture at a high level helps you spot these bottlenecks.

PR size. Large PRs take longer to review. Engineers know this, but deadline pressure sometimes leads to big, monolithic submissions. Smaller, incremental PRs move faster through review.

Rework cycles. If a PR gets sent back for changes multiple times, that is rework that was not in anyone's estimate. Frequent rework can signal unclear requirements, which is something you can help fix.

A practical tip: ask your engineering lead about average review cycle time. If PRs typically take less than 24 hours to get reviewed and merged, your team is in good shape. If it is consistently over 48 hours, there is a process issue worth investigating.

You do not need to pretend to understand the code. What you need is the right set of questions that surface useful information without overstepping.

"How big is this PR likely to be?" This helps you gauge review time. A 50-line change will fly through. A 2,000-line change will not.

"Who needs to review this?" If only one person can review it, that is a risk. If the team is cross-trained, reviews happen faster.

"Are there any architectural concerns that came up in review?" This is gold. Engineers discuss system design in PRs all the time. Those conversations often have product implications, like performance limits, scaling constraints, or migration needs.

"Is anything blocking reviews right now?" Sometimes the answer is simple: too many meetings, competing priorities, or someone is out. Knowing this lets you adjust expectations before a deadline slips.

"Would it help to break this into smaller pieces?" This is a collaborative question, not a directive. Engineers generally prefer smaller PRs too. Sometimes they just need permission to ship incrementally instead of delivering everything at once.

The key is framing these questions as partnership, not surveillance. You are not auditing the engineering process. You are trying to plan more accurately and remove blockers.

One of the biggest challenges with the code review process is that it is almost entirely invisible to product teams. You see tickets move from "In Progress" to "In Review" to "Done," but you do not see what happens inside that middle column.

This is where tools that bridge the gap between engineering workflows and product visibility become valuable. Glue gives product managers a window into codebase activity without requiring them to read code. You can see where work is concentrated, which parts of the system are getting the most attention, and where review bottlenecks are forming.

It is not about micromanaging. It is about having context. When you walk into sprint planning with an understanding of where engineering effort is actually going, you make better prioritization calls. When you can see that a particular area of the codebase has been a source of repeated review cycles, you can ask smarter questions about scope and technical approach.

Product managers who understand the code review process build stronger relationships with their engineering teams. They estimate more accurately. They catch timeline risks earlier. And they ask the kinds of questions that make engineers feel supported rather than surveilled.

You do not need to become an engineer. You just need to stop treating engineering processes as someone else's problem.

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Should product managers attend code reviews?

Not typically. Code reviews are a technical process, and your presence can change the dynamic in unproductive ways. What you should do instead is stay informed about review outcomes, ask about architectural decisions that surface during reviews, and maintain open channels so engineers can flag product-relevant findings. Your involvement is about context, not attendance.

How does code review affect product timelines?

Code review adds time between "code complete" and "shipped." This can range from a few hours to several days depending on team capacity, PR size, reviewer availability, and rework cycles. Most engineering estimates do not include review time, so PMs should factor in an additional buffer. Tracking average review cycle time helps you estimate more accurately over time.

What should PMs know about code review?

PMs should understand that code review is a quality and knowledge-sharing practice, not just a gate. It catches bugs, spreads system knowledge, and surfaces architectural decisions. The most useful thing a PM can know is how to ask good questions about review health: queue depth, cycle time, rework frequency, and reviewer bottlenecks. This lets you plan around reality instead of estimates.