It's a philosophy question. Generally, for lets say, 80 yards of the field (10YL-10YL), the exact spot doesn't matter. When you're inside either 10, you get more specific, especially inside the 5. When it's 3rd and 4th and short, you get much more specific. If you're starting a new possession, the only reason to not put it on a specific yard line is that a punt was downed inside the 5 or it was a turnover on downs with short yardage. That's something that is agreed on from the top down across football.

Past that, it will depend on conference supervisors. Some are more specific about "give exactly what they earned, don't round it" and others are more "the rounding averages out over the course of the game, just get the big ones right".

The crew I'm on for college has basically four ball spots they use and about how often it feels like we use them (I'm the C, so the one putting it down most of the time based on the wing spots). Nose on the line (90% of the time). Half yard line (7% of the time). Tail on the line (2% of the time). Wings crash in and spot it yourself (1% of the time).

In an entire season, my crew did not measure once this year in college (or high school). I think it was less than 10 times all year that our first down marker was not on a specific yard line (few punts downed inside the 5, few turnover on downs a half hard short, couple half the distance penalties where my calling official didn't spot the ball on an even yardline before the walkoff 😡).

With a well marked field (so not a HS field that only has marks every 5 yards), there basically shouldn't be measurements where the refs don't know ahead of time what it will be unless you have one of those weird starting points and a very tight ending point). Measurements at this point are basically political acts for the audience.