Oops: I made an error:

"eighth notes quantize at 100% to ticks 24, 48, 72, and 96, etc."

Obviously this is wrong. Eighth notes quantize at 100% to ticks 1, 24, 48, and 72, since (doh) they start theoretically on the downbeat.

See how easy it is to slip? And before you know it, your whole pattern is off in outer space . . .

But it is helpful to learn some of these values (e.g., also for swing triplets), since when you check stuff in microscope mode you have a better sense for where the notes are "lying" in the measure.