The military does not demand abstinence from sex for years - if they did, it would be an epic disaster. The relationships (sexual and social) that are prohibited are very specific in nature [1]. Soldiers have sex with civilians when on leave in the countries where they're stationed, they have sex with other soldiers they they don't have command authority over and that aren't in the same small unit, they have sex when they're back home between tours.
Please address the central point rather that seizing on an ambiguity in my post.
That point being, that sexual activity in the armed forces is still controlled and sometimes that drive cannot be satisfied for relatively long periods, and this is commonly accepted.
I am trying to address your central point. Your point is, as far as I can understand, "if it's okay for the military to control soldiers' sex lives in X, Y, and Z ways, why isn't it okay to similarly control teenager's and unmarried people's sex lives?"
But the kinds and degrees of control that work successfully are totally different from the kinds that you're suggesting. The "seizing on an ambiguity" is actually seizing on the fact that the policies you claim support abstinence's effectiveness are not policies of abstinence.
Again, you seem to conflate abstinence with permanent virginity. No, absolutely not.
This is really, really simple. Are you not supposed to have sexual contact for X period of time? If yes, you are abstinent for that period. The period varies, sometimes longer, sometimes shorter, but the definition still applies.
That would classify "don't have sex until the weekend" as an abstinence policy, which is ridiculous.
If X period is repeating on and off on semi-regular schedule, then it's not an abstinence policy. That's just scheduling sex. If it's a single continuous period, then it might be an abstinence policy.
[1](http://www.army.mil/article/138222/Army_updates_reg_defining...)