As a PhD student you are optimising for a goal with a long time horizon (in the first case to complete a PhD, but then perhaps also to obtain a permanent research position, which could take much longer) and it is hard to determine the correlation between any given intermediate action and eventual success (whatever you define that to be, but two large components could be prove beautiful theorems and get a job). This brute fact lies at the root of much stress and uncertainty. How does one prove beautiful theorems? How does one get a job?
Well, who knows, but certainy not by trying to directly optimise for a goal with a decade long time horizon, and this degree of uncertainty! You have to develop shorter term proxy goals, and it seems to me that part of the job of a supervisor is to assist in that development. If you want to prove beautiful theorems and get a job, then since it is difficult to infer from first principles the algorithm for doing either of those things, a r