One thing to remember is that the published plans have been tested and re-tested and adjusted and tweaked and . . . . . Whereas if you create a personalized plan and "Optimize", you get whatever the algorithm spits out, with no sanity checking.
I use the plans frequently, but I don't think I've ever used one directly as it came out of the optimizer. I always make rearrangements, and end up with preferable plans that actually take less projected time. (The optimizer uses a genetic algorithm, which will generally get you a good answer, but it isn't guaranteed to find the *best* solution.)
you also have to be ready to be flexible. Some of the items on your plan are going to be scheduled at specific times, so if you're running ten minutes late, you don't just see FotLK ten minutes later, you have to switch to a later show, and now you're adjusting the plan on the fly. Hence, it's good to review your plans in advance, to see where the hiccups might be and what you might do if they arise.
Another thing I tend to do is drop in two or three ten minute rest breaks, not because I plan to stop and rest, but because it gives me a buffer when stuff happens or something just takes longer than I expected. From my experience, when you start falling behind on a plan, it's really hard to catch up, especially since I engineer my plans to have not much slack time.