I think there is a distinction between asking questions because you really don't know and want to learn and asking questions because you doubt you Dom (questioning Him/Her or His/Her task He/She set) or are trying to get a way NOT to do a task (or whatever).

The first should be encouraged. But i agree with denuseri and ksst. Sometimes you have to keep quiet and 'just do it'. Not because all your questions are answered, but because you have built enough trust in Him(Her).
Because submitting is an act of your will. If you question the Dom/me everytime before you submit, maybe you should take time to see if you have really done that (act of will.)