Like you said, many of the forecast sites (like Windfinder) aren't real reliable for accurate MPH predictions. However, if you use the data for only checking trends (ie, is the wind increasing or decreasing), like what day this week is going to have the best wind conditions, it is invaluable data, and has never let me down. But then again, I'm retired, and have ultimate schedule flexibility, so I can pick and choose the best days (unlike you working stiffs!).
As an example, yesterday I went shad fishing, and Windfinder showed high winds in the morning, with the wind decreasing steadily throughout the day. So we got a late start and fished until dark, and sure enough it was correct. The early afternoon fishing was tough, with 15-25 winds, but by nightfall the wind died enough to be very fishable and I scored another 30 fish day! I was parked on the honey hole and kept debating about moving to another spot that had the wind blowing in the right direction, but we toughed it out and didn't move, which was a good thing because a bunch of other people were eyeing the honey hole throughout the day, but we had it covered!!! So Windfinder saved the day because I knew what the wind was going to do, even if the MPH weren't accurate (WF said only 12-15 MPH).
My buddy Jim breaking a rod on a shad. Two rods sacrificed their lives that day, fortunately none were mine!!!!