I don't think any one can answer this. We can only tell you our experiences! Because of course, every glider is different. Here's my experience!
I started with two neutered males. They were 1 1/2 years old when I got them. They have been together ALMOST their entires lives, just the two of them. Then I got a young female and started my intros (after quarantine of course) in february or march of this year. Needless to say, they are still not integrated. I had to eventually find another lone female and was able to successfully get the two girls together. So now, I have two cages with two gliders in each. I still try to let them all out at once every now and then, and yes, they still fight.
SO, that's my story. But maybe my gliders are just happy being in twos. Who knows!