HM
Worth 7 points before any premium square, and the 7th highest-scoring of 96 — tied with 2 others.
HM extends into 2 three-letter words, which is the 7th least extendable of 96 — tied with 2 others. That is the number worth memorising: a two-letter word is a place to put tiles, but a well-hooked one is a place to put them where the board stays open.
Every hook
- O→OHM
- M→HMM
Not all of them are equally reachable, which a bare count of 2 hides. HM hooks on 2 distinct letters, and the ones you are likeliest to be holding are O (45% of opening racks) and M (14% of opening racks). The rarest is M, at 14%.
How often you can actually play it
Out of an opening rack, 1.61% of the time you hold the letters for HM outright, the 5th least likely of 96 — tied with 2 others. Counting a blank as whichever letter is missing lifts that to 4.85%, though spending one of the two blanks on a two-letter word is rarely the play. Exact hypergeometrics over the 100-tile bag, not a simulation.