maybe this will help: Rambam may be looking at the same issue from different criteria. For example, in one place recommends to sleep 8 hours and wake up at sunrise, and in another – that real learning happens during night. This works together only during winter at most latitudes. So, one advise is for those who want to be healthy, another – those who want to be learned and you can’t always achieve both.
So, in this case, if you are optimizing learning than listen to hilchos of learning. The other one may be according to R Leff.