This seems like a suitable follow-up topic for my last post.
For health reasons, the prostate must be discharged regularly. The prostate will it regularly fill due to semen production but as it fills it will reduce the capacity of the bladder, causing more frequent urination. Excessive backup can cause painful swelling of the testicles, prostate, and the plumbing that connects them. In addition to normal build up, toxins will build up as well. Regular discharge clears the prostate of said toxins and improves long-term health.
When long-term chastity and orgasm denial come into play, regular milking is recommended in place of normal ejaculation. This is normally performed via prostate massage but it can be achieved in other ways, at least one of which can ruin the ability to orgasm naturally.
The appeal of milking in orgasm denial is that if done slowly and in the absence of stimulation to the penis, the prostate should discharge without an orgasm. Sexual frustration will not be relieved and none of the post-orgasm sub-crash side effects will occur. Since I have never been milked I cannot verify this through first-hand experience but those that practice this regularly seem to have found common results. I have experienced non-anal milking techniques and can verify that the "slow dribble" semen discharge has the same reported results.
It's been only recently that I've really considered the possibility of being locked up in chastity for an extended period of time, so while milking has been something I've researched, it's not something that I've really thought about deeply on an emotional and submissive level.
Looking at it now leads to a few "what if?" type fantasy questions and the potential psychological and submissive reaction.
Milking in itself is a bit humiliating and symbolic of deep dominance and submission. The Domme wants to much to prevent you from achieving an orgasm but does value your health enough to keep your plumbing clean. The thoughts that a man's sexual pleasure should be ignored, that his post-orgasm behavior is inferior so orgasms should be avoided, or that he should only cum while being violated all speak in some way to my submissive nature (my brain says no, my inner sub says yes). The term "milking" itself conjures up images of a domesticated animal being drained of its fluids.
The penis as a flesh and blood dildo.
Most Dommes I know prefer sex with an actual penis. After a prostate milking a sub's cock can still be aroused, but it will supposedly take hours to days for it to recharge enough fluid to actually ejaculate. So... after he is milked she can ride his cock for hours without worrying about him cumming and his unrelieved sexual frustration will grow and grow. I can't really say much about this except that I think it's hot.
A mind fuck can be applied with this same knowledge. If a chaste sub is promised a release and X number of minutes to jerk off and orgasm as many times as he can, milking him immediately before release will rob him of the orgasm and his attempts will be in vain, only contributing to his sexual frustration.
Creating an association.
If a sub is only allowed any form of ejaculation (with or without an orgasm) through prostate stimulation it seems likely that a fetish association would develop over time. In these cases the sub may equate ejaculation with anal violation and begin craving that as his primary means of sexual relief. This would be quite a mind fuck to turn a man who once craved sex into a sub that shakes his ass and wants to be pegged via strap on. I doubt many Dommes would actually want this to happen, but I'm sure there are at least a handful.
A different kind of association.
This might seem a little bit unfair in some ways, but if enough negative reinforcement were placed on a sub's post-orgasm behavior, and his deeply submissive state while mired in prolonged sexual frustration were to be positively reinforced, it could be possible to make a sub actually prefer to denied orgasm. I think this is a two-sided coin in that I would guess that a Domme would be proud of a sub's self-control if he preferred to serve her well without an orgasm. On the flip-side, a sub that doesn't crave an orgasm is probably a bit boring and less fun to fuck with.
Putting it all together.
What I can realistically gather from these ideas are that in most cases, turning the sub's cock into a human dildo of great endurance is probably a good thing, yet reducing the sub to an ass slut or robbing a sub's desire to orgasm probably aren't desirable outcomes. Thus, there is a delicate balance to find.
From what I can gather:
-A sub should receive enough penile stimulation or actual orgasms (even if infrequent) to keep him craving them. He can be kept further off balance if shame is associated with actual stimulation or orgasm.
-Milking should be unpleasant. This can cover both physical and emotional angles. Uncomfortable restraints, a ritual beating before and/or after, and humiliation could see to that outcome.
-Chastity periods between orgasm should be of a known duration. That's not to say that the duration can't change due to reward or punishment, but having a set date will keep the sub's anticipation for his next orgasm up and prevent him from defaulting into an undesirable state.
As a sub, I can say that my deep subspace persona starts to hate itself both immediately before and after climax for my loss of focus and obedience. This gives milking some appeal when thinking as a sub.