I would not exceed more than 2 days off in a row unless you are doing a decon break.
I like to do 2 on 1 off and take a 5 day break every 2 months or so.
I feel like if I take any more than a day off it takes forever to get back to fatigue doing manuals, but it depends entirely on your routine, intensity, and your body’s ability to heal itself. Some heal faster than others.
I like to think of it like a graph with three horizontal lines. The first is zero stress, or your penis as it is when you are not doing PE. This line is on the bottom. The second line is fatigue. You have to do enough excercise to raise the condition of your penis from the first line to above the fatigue line to make any gains. The third line is the injury line. It is on the top and should NEVER be crossed. If PE raises the condition of your penis and rest days lower it then the goal is to hover between fatigue and injury without letting your penis go back to its normal state.