I have made the occasional plan that works better than an Optimized one, but they are few and far between. I think the issue here is that you are adding all of your FPPs at once and then re-optimizing. The problem with this is that FPP choices affect each other, so you are not getting the best result. One trick to avoid this is to optimize (several times), add the FPP that willl give you the greatest benefit, re-optimize, add your next FPP choice, etc.
I have a post on here that goes into more detail on this: