Wanted to address this, no this wouldn't work. Every time somebody deciphers whether they're in a genjutsu, they figure out the situation they're in isn't real therefore, by your logic, one could just ignore the illusion. However that's not how it works. Only time we've seen such a case was when Iruka used genjutsu on Sakura as a test to see if she were ready to take the chuunin exams. She walked right through and ignored the illusion. However there has never been a time elsewhere where that has happened.Imma stick to calling you Kevin regardless. :3
I know a few. One is full body surges of chakra, like Nagashi, and add weight, which will flush out the external chakra in a sense. I know of the Kai technique, and that a friend can wake you up as well. And you can inflict pain upon yourself (I don't understand the details of this, like how much pain is needed for what rank of gen). Oh, and I'm under the impression that sometimes you can simply ignore a genjutsu, like if the gen showed you a number of snakes approaching you, and you realize that the snakes aren't real due to your opponent previously summoning a goat, you can simply ignore the snakes and continue to attack your opponent, thus not wasting time on the fake snakes.
When Itachi cast his genjutsu on Naruto during the arch where they were rescuing Gaara, Naruto understood he was in an illusion, however, he couldn't break out of it simply by knowing he was in one. He attempted to use Kai but it didn't work. The illusion used, though it's counted in the RP as one, was not a dojutsu technique, rather an ordinary genjutsu tech that Itachi had the ability to cast with merely his finger. Genjutsu hasn't been expanded upon much in the series. In the filler arch where it dated back to Naruto and Jiraiya's journey's between the origional series and Shippuden showed what happened when Naruto and Jiraiya were in an illusion. As well, with the Giant Clam of the Second Mizukage, everybody knew they were under an illusion but they couldn't simply break out of it by knowing.
The reason for this is because genjuts affects the chakra in the brain. It affects the five senses and one's perception. However, people can still use their brain to understand they are within an illusion but that doesn't do anything to deal with the chakra that is affecting the parts of the brain that control your senses like sight, touch, smell, etc, etc. You need to use one of the release methods to forcibly rid your body of the chakra that is infecting you and causing the genjutsu.
The con you put is a result of using almost any means of release from genjutsu. If you take the time to hurt yourself or to even use Kai, you're wasting time to get rid of the chakra while your opponent follows through with their other attacks. Possibly, the only exception would be for the last method.Well, I guess that momentary feeling that accompanies damaging your body also disturbs the flow of chakra. It's known one cannot maintain his string of thoughts when in pain, he cannot keep observing his surroundings. During severe pain, for a split second, you do not see, hear, smell or feel. I'm guessing this works whether your senses are unaltered or altered.
Using the pain method has pros and cons. Of course, this saves you a jutsu's spot by not using kai as it's a freeform move. However, this is only an advantage over using the Kai technique. If you're being attacked while caught in a gen, and you waste time inflecting damage upon yourself, you might not have enough time to react to the incoming attack.
Also, the more pain the more damage done to your body, the more damage done to your body the slower and weaker you become.
I guess I can conclude that pain, just like Kai, will stop techniques requiring a continuous flow of chakra such as sensory or fire streams.
Also, lets not forget the degrees of pain you inflict based on the jutsu. The stronger a genjutsu is, the more pain you'll need to inflict. Stronger genjutsu affect the brain and your perception of your five senses evern more so than weaker so a stronger spike of the body is needed in order to re-establish your sense of reality from fiction. Where as; a D-ranked genjutsu technique can probably be released by biting your lip or a rather shallow cut with a kunai, an S-ranked genjutsu will require a significant wound which may end up hindering you in a fight.
The results, if your opponent delivers several high class gen techniques at you and you are only using pain as a method to release (for the sake of the example we'll say its the only way) then you'll have done a significant amount of damage to yourself to the point your mobility and ability to react are lowered.