Again, I regularly deviate from my guideline. It's a very good guideline, but as with all guidelines, if you stick to it always you will suffer. For a sustained, four-notch flap turn, roughly 170 M.P.H. gets you the best results (more like 165 when lightly loaded). That doesn't mean I recommend going 'round and 'round at 170 non-stop.
As for the original poster, he can try out my suggestion, or he can ignore it. It's up to him, and there's enough opinions that he can make an informed decision after testing.