Is it imp to vary intensities?

Hi all,

I know how imp it is to have rest days. But is it also imp to vary the intensities of your workouts? I’m a super intense person and tend to feel I didn’t get a good workout unless I’m completely wiped. But this isn’t necessarily the healthiest approach, right? I’m currently doing fb 30, and I notice that there are both super intense days as well as easier days. I shouldn’t do more on the easier days to reach exhaustion every day, right?

Thank you!!