Drill PokerTwenty blinds from middle position is the depth where the shove turns from a core tool into a specialty play. The equilibrium range is 16 hands, about 7% of combos: pairs from 99, suited aces from ATs, AQo+, kings from KTs, QJs.
Push from MP, 20 BB stack
There are no offsuit kings in the range at all — at this depth even KQo doesn't justify risking twenty blinds to win one and a half.
The standard line for every one of these hands is an open raise of 2–2.2 BB: postflop poker exists at 20 BB, and premiums earn more from it than from an instant all-in. The shove becomes the best choice in two scenarios. First — short stacks behind you who happily call wider than they should: an all-in against them is pure value. Second — a table where every raise you make meets a re-shove: then it's better to put it all in at once and take their fold equity for yourself.
Hands like 66–88, AJo, KQo, which intuitively beg to go all-in "before it's too late", don't shove at 20 BB — they have enough depth for a raise or a fold. Compare with 15 BB, where some of them are still in play, and with the opening chart for normal depth.