Remember, specially if you are a singer, a session with an accompanist is about ensemble work. It is not like any other lesson. If you are still very insecure with your part of the music, do everyone a favor and stay home and practice. If you can’t play your music yet and keep stopping every few measures, you are wasting the accompanist’s time; more so if you are working out technical details and your accompanist is sitting in a corner waiting for you to finish.