I was unusual as a bookstudy/service group overseer...
I always felt that asking for time was no different than asking for a monetary donation and that was anathema. I told the bros the same and they felt I needed to "shepherd" more. So I did. I got with each person in the group privately, asked them if they really wanted me to bother them about their "time". I explained why I felt this was none of my business and what the bros were pushing and why I felt they were wrong. I told them that I could make it easier on them and easier on me if they would just let me report zeros as the default unless I was otherwise notified. I told them that we were all supposed to be "growing up into the head which is Christ" and that personal responsibility was the direction Jehovah's Chariot was moving them towards (since at the end Jesus hands his Kingdom over to his God). I told them that if they wanted to make use of me as a "personal spiritual trainer", I would be happy to make myself available, but that their dedication was theirs and their relationship w/Jehovah was theirs alone and it was up to them what they would and would not do and I would respect that.
After that I never had to bother with time again. If it wasn't there it was a zero, but funny thing was I never had to actually report a zero but once. All the other bros were wondering what I'd done to make everyone so regular. I told them that I just shepherd them. (which I did, but not the way they they thought of it)