Is it normal to experience ups and downs in terms of ADHD symptoms?

My husband is in denial but almost certainly has ADHD, but there are periods of time, especially after an especially big screw up but, also just in general, where he exhibits better control (or is it just masking?) of his symptoms.

It's crazy making for me.  We've gone through a bit of time where's he's been pretty even-keeled emotion-wise and pretty reliable otherwise but...this last week was a s*** show culminating with today's complete disaster which resulted in a late dinner, an overdrawn checking account and two stressed out parents. (One of whom was stressing the other out due to unmanaged ADHD behavior)

I, of course, blew up, making me the bad guy.

I suspect we'll go back to a period of "normal" until something else comes up.

Are the ups and downs normal?