IMO it's not really cheating to reuse assets. I think the only time it ever becomes "cheating" is when you, say, re-frame a panel in a way that doesn't make sense for the story or the emotional vibe you wanted to portray (e.g. a panel calls for an object to be seen from below to make it seem overwhelming, but you have a version from bird's eye view and change the camera angle to accommodate your existing asset, throwing your narrative into disarray).
That being said, I almost never reuse. BUT, I kinda have sketchy, whimsical backgrounds and it's usually just a matter of it being faster to draw from scratch than trying to reuse what I have. I think reusing and repurposing existing art is totally fine for comics. They take a lot of time to do!