@Avery
You are mixing up two very different things.
1) Belt as protection against sexual assault
2) Belt to protect you from giving in to sexual urges that would cause you to violate your goal of chastity.
Personally I don't consider number 1 a good use, because it is potentially getting the attacker more angry and violent. But if you are a victim, I can see how at least you would feel protected.
For number 2 is is of course all about how acceptable fails are to you. If I was making the decision to actually go for a no orgasm lifestyle, I would not want any fails. Or in other words, fails would be worse than the disadvantages of being in the belt 24/7. In your case obviously you consider fails as no big deal, so your priorities are reversed. Your approach is 'belt as little as possible and just as much as needed', while based on the different priorities, my approach would be 'belt as much as possible with breaks as little as is necessary.
Nothing from with either approach, I just think everyone needs to find the right approach for his/her goals.