It has been my experience that over time giving oneself 110% to one's Mistress is in many ways partaking in a right of special passage.

Safe words become more for safety and less for session management.

i remember a recent session where a Mistress had taken me so far into subspace that i was, for all intents and purposes, speaking in tongues. Much of what i said and begged for was from deep inside my most secret and wanton sub/slut fantasy world. i later realized that i let a lot more of my deep, dark needs out of the bag than i might have wished.

A great Dominatrix will file those wanton confessions away and in future sessions utilize the ones She thinks will give Her the most pleasure and take Her into Domme Space. The sub has already told Her that he needs more She just needs to decide which more is better for Her.