This is a constant source of controversy.
We know this. Often when people take a break from PE, they will see gains. Those gains may sometimes be related to an EQ boost from not undergoing the stress of PE all the time but I don’t think that’s a fair description of all rest related gains.
You could argue that the rest period is a holdover from body building and not really appropriate to PE, which is not working on muscle and doesn’t have the same limitations.
Group experience suggests that rest days may be effective. Common practise is to at least take rest days for girth work. Hanger and extender users often do not take rest days. To me this doesn’t particularly make sense.
On the basis that less is often more and that PE should be ramped up, it would make sense to start with 2:1 or 1:1 and not align this to the week. As you progress, you might switch to 3:1 and then to 5:2. All this increases the work done in a week or increases contiguous work. Some people do not use rest days at all.
Use EQ as a guide. If you are doing too many days on in a row, this may impact negatively on your EQ. With a lower EQ, PE can become less effective.
I know that’s not a cut and dried answer but I think it states some of the thought that has gone on. If someone can think of extra detail to add, please do.
Personally, I found rest days were essential, by the end of my PE I attempted to maximise work done during on days and I needed the rest days to recover. I think that some people plug on with daily PE on reduced EQ and this my not be as effective.