When the hour hand is on 9, you can see at a glance it is two hours from 11 and three hours from 12 without needing to do the calculation in your head.

I don't think most people need to do a mental calculation to know that 9 am is 3 hours from 12. That's just a fact that's easy to remember since you're exposed to it so often.

When the hour hand is in the upper right, you know is it shortly after noon or midnight depending on how bright it is outside

And when the digital clock says "1" or "2" you know it's either afternoon or the middle of the night. Even better, if you're using 24 hour time you know precisely if it's afternoon or early in the morning even if you're in an underground bunker.

When looking at the minute hand, if you see something started at 2:10

Yes... you can just remember the "minutes" part of the time on a digital clock was too.

15 minutes is easy to figure out because it is a quarter of the circle.

15 minutes is easy to figure out on a digital clock too because it's ultra simple math to just add or subtract 15 from a number below 60.

[–] snooggums@piefed.world 1 points 28 minutes ago

I'm imaging you dismissing the idea of a pie chart because obviously 8 is twice as large as 4 and knowing 8 is 2/3 of 12 is just a fact people know because they are exposed to it so often.