And even if you DO post in small communities, half the time it's a toss-up as to whether anyone will see it.

I'm not sure about lemmy, but reddit was roughly 50% US users, so it was a good bet that if you timed posts for "early morning" US browsing or "after work" EU browsing, your post would do well.

Idk lemmy's demographic breakdown, but it seems more generalized (imagine that, a diverse fediverse!) around the world, so it's hard for me to tell when the most users will be active.