Using data from a major commercial online game, Des-tiny, we track the development of player skill across time.From over 20,000 player record we identify 3475 playerswho have played on 50 or more days. Our focus is onhow variability in elements of play affect subsequent skilldevelopment. After validating the persistent influence ofdifferences in initial performance between players, wetest how practice spacing, social play, play mode vari-ability and a direct measure of game-world explorationaffect learning rate. These latter two factors do not af-fect learning rate. Players who space their practice morelearn faster, in line with our expectations, whereas play-ers who coordinate more with other players learn slower,which contradicts our initial hypothesis. We conclude thatnot all forms of practice variety expedite skill acquisition.Online game telemetry is a rich domain for exploring the-ories of optimal skill acquisition.