@Nosfentor
If your best team is full of gear10 toons, then make sure you have a couple of squads of gear9 toons before working on boosting your g10 toons up to g11.
If you have 5 x g11 toons and all your other toons are g8 or less, then when your g11 toons hit a node they can't beat (either because they're the wrong squad for that opponent or just bad RNG) there's no one that you can call on to back up your big hitters - if g11s can't do it, even when they're the wrong toons for the job, then g8s can't do it even when they're the right toons for the job.
You need 10-15 toons that are close to as good as your best 5 if you want a better chance of finishing GW.