The monkey holds 申, three to five in the afternoon — the day's work nearing its end, the hour that starts needing improvisation. The monkey stands for the workaround: not force against force, but finding a way round that nobody thought of.
You'll recognise it here: rules are negotiable information to you rather than boundaries; you learn extremely fast, fast enough that you often lose interest before finishing; and constraint is when you're at your most inventive.
Running well, the monkey is whoever unlocks the dead end: everyone says it can't be done and you ask whether it has to be done this way, and the whole thing changes shape. Blocked, it goes two ways. One is spending the cleverness on avoidance — finding the shortcut and stopping there, so a lot of ability sits at a passing grade. The other is boredom: once you've seen a thing's mechanism you want to leave, so the CV is impressive and nothing on it is deep. What the monkey practises is staying with something hard enough. Difficulty is the only thing that holds you.