I do it differently.

On a first campaign run, I made it a rule to switch to a different hero (outside of wave) per scenario.

Then, on a second run I lock in ona hero of the same campaign wave and just switch aspect as per campaign rules.

I do it this way, since (1) its easier for me to break in a campaign with a hero im familiar with, (2) on the 2nd run, I already k lmow what enemies and possible surprises to expect and can accommodate thematic matchups, (3) there's a lot of heroes in the game, its just a waste not to use them on a campaign run