Also, try to stop thinking in terms of A team and B team.
There are specific squads that work very well in arena... due to toon attack order. In GW, this goes out the window. Don't lock yourself into specific squads. There are innumerable oddball squads that will rock GW. Sometimes you have to sub in only one or two toons to make a difference, and save full TM toons for later.
You have to analyze your harder nodes and figure out how much "toon capital," which you have previously saved up in node 1-5, that you need to spend to get by with the least cost to your bench.
And the only toons on your bench that matter by node 11 are the ones that are not on cooldown and which have good TM.