My latest edition of Keyzen MAB measures your typing performance on trigrams using an English language corpus. Trigrams are chosen after each word using the dynamic thompson sampling algorithm. Weaker trigrams will be shown as much as necessary to minimize regret (time spent practicing trigrams you are already good at). Initially each trigram has a uniform probability distribution function. This changes with practice so bad trigrams are practiced appropriately. The dynamic component of thompson sampling ensures that older trigram practice instances are weighted less than newer ones, ensuring that your improvements in trigram speed are captured in the underlying statistical model of each trigram.