This is the question that gets asked over and over in every discipline. It's completely individual. Each person will be able to handle different amounts of work, and that amount of work will vary even for them from week to week and month to month.
The key I think is keeping accurate records of training, nutrition, sleep, bodyweight, body comp, etc. so you can actually go back and analyze what's happening. Too many times people make wild adjustments to their training every 2 weeks, but it's based on nothing substantive, just shots in the dark. If you have records, you can see correlations between feeling like shit and a given volume/intensity/type of training, poor nutrition, poor sleep, etc., and make intelligent changes to compensate.