That sounds horrible. I don't know how people stand to work in those conditions.
But some people will put up with a lot for half a million dollars a year.
You do a lot of small changes (<100 loc) that get reviewed often. If it doesn't get reviewed often then the whole idea of continuous development breaks down.
Argueable you have 8 hours of work a day. How many of them do you need to write 100 loc? After that 100 loc or maybe 200 take a break and review other people's code.
Plus you also have random meetings and stuff so your day already fragments itself so adding a code review in the time before a meeting or after is "free" from a fragmentation standpoint.
I have an issue at work that will likely be solved by a single line change. But figuring out which line it is is going to take awhile.
So it really doesn't matter when the review gets done. I mean, even a week and it's fine.
My ideal system (for work) would be something like: after 2 days, ask for a review if the reviewer hasn't given it. After a week, warn them the PR will be auto-approved. After 2 weeks, auto-approve it.