Drill PokerTwenty blinds on the button is 53 hands, a quarter of all combos: every pair, any suited ace, offsuit aces from A8o, kings from K7s and KTo, queens from Q8s, QTo, JTo, JTs, T9s, 98s, J8s.
Push from BTN, 20 BB stack
Even at a depth where the early positions have long forgotten the all-in, the button keeps a quarter of the deck in the shove — that's how much having two players behind you instead of seven is worth. But the chart has to be read correctly: these are hands whose shove doesn't lose to equilibrium, not hands obliged to go all-in. The button's default at 20 BB is an open raise of 2–2.2 BB with nearly half the deck.
The shove beats the raise in a specific environment: blinds who re-shove over your every open, or short stacks in the blinds where a raise provokes the all-in anyway — then it's better to set the terms yourself. Against passive blinds a 20 BB shove simply burns value: they would have folded to a raise too.
Boundaries for self-checking: A8o still shoves, A7o no longer does (compare with 15 BB, where A4o held on); 22 stays in the range at any button stack; T9s survives even the twenty — connectors die last.