They really don't make it easy at Full Tilt. At Stars it's not really a problem. There's plenty of time in the bank if you have a ton of action and a big decision.
With experience, however, the late game becomes pretty much automatic. Since this is when most of the action overlap occurs, it shouldn't be too much trouble. I play six tables started ASAP after one another, and I only had a problem once when I made it to heads up simultaneously at five tables.
But basically what you should do is find a number of tables that is only occasionally uncomfortable. Then after settling in with that number, move up by one.
BTW, are you playing very low stakes? If you aren't, it's very rare to cash in upwards of 75% of the tables. Perhaps this is an extreme rush of luck, in which case I don't necessarily think you need to cut the number of tables. If it only gives you occasional discomfort, it is a good thing IMO. That discomfort will help you learn to multitable better.