I regularly do 6ml in the quad and 3ml in the glute no issues and I dont warm my gear.
Currently its 2ml and 3ml so no biggie, I could do 1 injection a week if I choose to, but its easier to split up.
IMO I would do an extra injection a week instead of trying to push 5ml, its too much a pain in the ass (pun intended)
With 6 site rotation you should be fine.
6ml in your quads??!?! that has to hurt, even if you have legs like coleman's...that's alot...I have done 4ml in my glutes, but there was a knot there for over a week...6ml's...how long till you use that site again?? I just would be afraid of a sterile abcess..when I inject 4mls in my glute (not often) I don't use the site again for over a week..2 or 3ml's, I can use the site again a week later with no issues, but everyones body is different