JO
Worth 9 points before any premium square, and the highest-scoring of the 96 — tied with 5 others.
JO extends into 6 three-letter words, which is the 18th least extendable of 96 — tied with 3 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
No letter in front of JO makes a word.
- B→JOB
- E→JOE
- G→JOG
- T→JOT
- W→JOW
- Y→JOY
Not all of them are equally reachable, which a bare count of 6 hides. JO hooks on 6 distinct letters, and the ones you are likeliest to be holding are E (60% of opening racks), T (36% of opening racks) and G (20% of opening racks). The rarest is Y, at 14%.
How often you can actually play it
Out of an opening rack, 2.84% of the time you hold the letters for JO outright, the 7th least likely of 96 — tied with 1 other. Counting a blank as whichever letter is missing lifts that to 8.86%, 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.
The only place a J goes
J appears in exactly one two-letter word, and this is it. If you are holding that tile and need two squares, JO is the whole of your options.