Somewhere in the back of her mind she was vaguely aware that she probably stop, although she hadn't really explored how long it took a Time Lord to recover from ejactulation. They were supposed to be mostly asexual after all, since there was no need for procreatation and of the Time Lords were a stuffy lot, she coudln't really imagine them approving of what she was currently do to her fellow Gallifreyan.
The Master was nothing if not creative however, and dispite the fact she could feel him in her mind beginning to loose control having him at her mercy in this way drove her on and while she was cruel the idea of stopping when he was so clearly enjoying her actions was not something she was willing to consider.