Dragan Stepanović - Should we be having this problem in the first place?

and 1 hour to get a review and PR approval, that means the wait to processing time ratio is 60/5=12, and flow efficiency is only 7.7%.

Do you really think that a system this inefficient is incentivizing refactoring and small steps?

And yet, I notice lots of people (thinking they are) bragging saying ‘We review PRs in one hour’.
Wait time matters only in relation to the processing/touch time and thus as part of the flow efficiency.

If you have wait time in the system (inherent to async work), I can always find you a batch small enough for which flow efficiency is so bad that it doesn’t make any economic sense to have a batch that small, which leads you back into bigger batches.

This will never be true for sync work (zero wait time).
And that’s why co-creation (pairing/mobbing) will leave you with way less cruft in your codebase from which you, your team, your product, and your customers are likely suffering from.

Working together works.