Super's stills aren't typically all that bad, especially face shots. Super's main art problems come from action scenes(though not as often in this arc) and on characters farther away from the camera. The average quality of the show is actually at a pretty solid place right now, but it still dips into not so great territory, but not all that often. I mean even 53 which people bitched about because of the fight still had fine art for like 95% of the episode.
DBZ was more consistent within individual episodes, but the art styles of the supervisors were wildly different, so we'd get one episode that looked consistently good followed immediately by one episode that looked consistently wrong. Super has done a surprisingly good job of staying on model most of the time, especially considering the time constraints, and we haven't had a single episode so far this arc that looked bad from start to finish, just episodes that have bad looking parts.