I fail to see the problem with this. If one or more member is having trouble with a part or change the best way to work on that is as a band. For those who aren't having a problem additional practice isn't going to hurt.
Also, in all my years in bands I never stated that someone was the one messing up (unless it was me). I always took that view that we aren't getting it right so we have to work on it.
I have no problem working on songs to get them right. We worked on one song for almost half the practice and we practice for 3 hours. The singer and BL/guitarist kept debating on the structure of the song. Guess what happened the next week? The same thing happened. Also I get the feeling that he never wanted me in this band.