I rest on rest days. I try to ride 6 days per week but no less than 5.
I did a long hard ride yesterday. My morning heart rate variability screamed rest. My TSB at -58.4 said rest. I would prefer not to have those numbers but the ride was a required qualification.
I guess my reasoning about rest is you get stronger only during recovery. If you have not recovered and you add more training stimulus, there is a chance you're just digging yourself into a hole.