re: Poker & Short Stack Games v Deep Stack Games
20bb is an awkward number to discuss with a limper - you can easily raise to 2bb and then c-bet 2.5bb into 5bb (with antes) and you'll still have around 16bb if you don't hit the flop and can't take down the pot which is a fine stack to play with.
Alternatively, if there is a limper and you have 15bb you can shove stuff as bad as A9/KQ and pick up around 3bb each time which is a nice boost to your stack especially as a lot of players limp/fold a lot at micros.
The trick is not to wait for a good hand but to take advantage of position. Say you are on the CO/BTN with 10bb and the players left to act are reasonably tight - I'd probably be shoving any 2 cards, especially if antes are in play.
When you have <15BB or so shoving very wide in late position because very profitable. When there are limpers, shoving with stuff like AT/KQ is far more profitable than suited connectors or A4 because you're far more likely to have them dominated or have two overs.
There is more variance in short stack games but they take less time because of stack sizes so you can play more, therefore variance is kinda irrelevant as it is possible to play a decent sample size and balance it out.