You're doing this retreat to make progress, right ?
If you are somehow stopped from crapping or stop leaking, you will eventually die. They are essential to your survival.
On the other hand, nobody has ever died from celibacy. My own experience has been that it makes the mind a lot calmer and stable. There is less guilt, shame, sloth, anger, and so on.
So the same thing occurs with the seminal fluids..... along with emptying them out via no-thought seems to take care of any further constructs being created from some actions.
So why do you need to repeat the process every week ?
I encourage that you observe the sensations that you're attached to with equanimity, and decide for yourself whether they are worth being addicted to.
I dont discourage masturbation in normal life, but I strongly discourage it on retreats.
I have been frustrated by my addiction to having to "let it out", and gradually through practice and contemplation of the negative effects, the influence of lust has come down to the point that I very rarely succumb to it.
I suppose we live in very different cultures and there is a huge difference in the level of sexual suggestiveness/freedom in the society. If I was living somewhere in the west or where the culture is more westernized, I'd find it more difficult to subdue my tendencies. Still, it's worth doing with strong determination. As I said, you'll not die ;)
Avi Craimer:
Rather than seeing it in terms of "excess fluid" I experience it as a build up of libidinal energy (maybe this amounts to the same thing).
Isn't that the very purpose of watching erotica ?
If you can overcome attachment to sexual sensations, then engaging in sexual activity is no more of a hindrance to enlightenment than any other empty sense experience.
Now, I am a straight man. That would imply I have absolutely no attachments to sexual sensations derived from a session of homosexual sex. Given thus, why would I will/intend to engage in such activity casually or otherwise? What purpose will it serve me ?
Overcoming sexual attachment and then having sex is just like that. A man cannot have an erection unless he is overcome with lust. Engaging in other empty sense experiences does not require getting subdued by lust.