when i was around 17 i stayed on for over six months. strangely I had no bad sides, i gained over 60 lbs, and did not crash when i came off. i was on 400 mg of brovel deca per week.
Bro, I don't mean this in a flame sort of way but please reveal your age. If you're young, like in your 20's, then the following might be interesting to you...
Say you meet a beautiful woman in a few years or even next year. You become serious and you both find that you will be together forever. She wants children but you cannot because you didn't want to come off of Deca occaisionally to let your body normalize. That would suck, believe me.
I love deca, and I'd love to stay on it indefinitely, but I'll be damned if I'm going to risk my long term health just to stay on indefinitely. Just come off when you're supposed to, get your body normalized and then go back on. Now that, you can do indefinitely.