I don't think schools put any thought along the lines you just did. I think schooling operates the way it does because that is just the easiest. It continues

I don't think schools put any thought along the lines you just did. I think schooling operates the way it does because that is just the easiest. It continues to operate that way because the people who decide how schools, especially colleges, are run are exactly the people who overachieved to a huge degree in that same environment, so they have their ego tied up in it being meaningful to do well in it. Take grading, why do they start at 100 and just take points off for mistakes? It's just easier, most people most of the time get most things correct (or at least most work isn't worth discussing) so it's less work to just skim the work and paint some red where necessary than it is to evaluate and explain how each part contributed to the final grade. The latter would require a lot of thinking and would take a lot longer. Why be very strict with timelines and time boxing of assignments and tests? Again, it is just practical and easier. Making everyone turn in work on time makes grading it less of a chore since you won't be grading this random assignment and that random assignment, you'll have a stack of 30 of the same assignment and you can get in the zone and burn through them with optimally low effort. The same with tests, why would we care if it took one student an extra week to get to mastery compared to a peer on test 1, and maybe vice versa on test 2? Isn't it better to encourage all students to reach mastery before continuing on, so they don't move to the next topic in the same class unprepared? Well then you have to have lots of equivalent tests, since once you give a test it is 'out there' and students aren't trusted not to cheat. I am confident there is no rational for any of the above besides it being practical and/or less effort for teachers, and it isn't questioned because the teachers had absolutely no problem performing in such an environment.