Sometimes people sign up for a one on one discussion with me and for some reason the discussion does not happen. I then communicate with that person and arrange another time. The original discussion report stays in my Tutor area. When we have the discussion I send out the discussion report. The system thinks the discussion took place as per the schedule.
So if you want to talk to a tutor but the time is inconvenient, you could try contacting him or her directly via email or their Wall. If you can find a mutually convenient time, you can still sign up for the discussion that is posted, but have the discussion at another time.
Just an idea.