I would ride at recovery, not endurance. If the ride starts to feel like work, bag it immediately. Do that on Saturday. Sunday I would do at least a 45 minute endurance ride just to maintain consistent frequency…before rolling out, review next week’s calendar just to keep in mind what you’re recovering for so you can remember that you don’t want to make an effort today, you want to make an effort THAT day.
I will frequently do a double session Saturday/Sunday followed by a recovery / Z2 ride Monday then a day off Tuesday for a HARD workout Wednesday.
Basically - don’t be afraid of a back-to-back and doing endurance on tired legs, but you do need to layer in time to recover afterwards if you do that. Also somewhat depends on your volume and how acclimated to it you are.
I’m always willing to just go do some light and easy .55-.65 IF no matter how tired I am. Whether that becomes .65-.75 and the length of the ride depends on when the next hard workout is. If I’m really questioning myself but just itching to get outside, I just go for a walk.