I’m tracking training and remember roughly how much time I should spend on Z1, Z2 etc. as well as strength but wondering how long a cycle should last before taking a rest and how long rests should be?
It depends. It varies per person. There are no hard and fast rules. In general, most people do two or three build weeks followed by one easier recovery week.
I’ve been feeling really fatigued this week and don’t know if I am doing too much and should incorporate a full rest week.
It sounds like you need a break. A good rule of thumb is to “do as much as necessary, not as much as possible”.
Overtraining is much harder to recover from than undertraining is to compensate for, so always air on the conservative side.