Seems like it depends on the song a lot. A lot of stuff that’s more “rock” varies enough that it’ll get noticeably off after a few measures, but more synth stuff tends to stay on beat better.

If there’s a particular measure that you can’t spot well in a waveform, you can always just place the measure marker such that the next measure lines up correctly. Basically just splitting the difference.

Also it’s worth mentioning that hitting T will do what Q does, but let you switch the time signatures, which can be handy for songs that switch regularly (pretty sure one song I started charting was four measures of 3/8 followed by a measure of 4/.