Not Quite
In order to avoid the penalty of carrying that escape tower all the way to LEO, you have to use it early.
If you use it early you're trying to pull the entire stack upwards and the extra thrust is just a drop in the ocean compared to the big dumb boosters.
If you save it till late, it gives you a last-minute surge, but you're already far behind track compared to dumping it early, so you don't win.
The important thing is to get it out of the way of the rapidly lifting stack as soon as it's moment is past.
(And with the Challenger experience, would you get much chance to use one, anyway?)