"Extremely high levels of sexual energy are being reached during sessions - at levels I probably would not have been able to endure for any lengthy periods during my early practice."

This is perfectly timed for me! I have been noticing in a sense, the opposite (in a good way!). I will have waves of increasing energy culminating in a spontaneously self-generating orgasmic "even" that lasts anywhere from 5 to 15 minutes or so at its peak and then fades gradually down leaving me feeling full and glowing w/ a gentle warm energy and zero desire for more "activity". If I just lie there and bask I get so relaxed I start to snore while wide awake! It is in some ways similar to the refractory period after an ejaculatory orgasm except that I feel full instead of empty! I think this is my body's current maximum threshold and is acting as sort of a built in circuit breaker. Whatever! I'll take it!!! I would imagine that after some period of integration at this level, the threshold will move to a higher level as implied by Zed above.