To be honest, I agree they should be able to be larger at times.
I had a lot of disagreements when I was on a new codebase, knew what I was doing and I was able to push a lot of code out each day.
The idea is to have them small, easily readable with a tight feedback loop. I argued that bootstrapping a project will have a lot of new code at once to lay the foundations and my communication with the team was enough feedback. If I split it up, each PR would have been an incomplete idea and would have garnered a bunch of unnecessary questions.
That said, I think it’s generally pretty easy to put out multiple PRs in a day, keeping them small and specific. As you say, half of the job is reading code and it’s nicer to give my coworkers a set of PRs broken down into bite sized pieces.