They might if one bothered toe listen real hard.

Not necessarily.

If the lift chain is too long it might just cause the flapper to hit the back extreme of it's range of motion and bounce back in the hole. If too shirt it might not allow it to get high enough to avoid being sucked back down into the hole
'Either way the result is that you gotta hold the handle while the fuck cycles or it'll drop back.

And then there's different kinds of flappers.
Some have a little float that keeps 'em up while the fluch cycles.
Some have a little tank with a small hole in 'em. That tank is full of water which causes the flapper to be heavy on the leeward side of the flap. This causes the flap to remain upright until the water flows out the little hole at which point the balance shifts and the flapper falls back in place.
Others are naturally buoyant.

Ya gotta pop the top off and watch the action to determine whether to give the chain more or less slack.

yes, that is the problem basically. his bowl fills way up because the onrush of fresh water isn't forceful enough to empty the bowl.