Except, if this "test" is true, you will be playing a game of chance. If you try to "beat the system" by booking your 3 FP+s for the morning, figuring that the window will then open up allowing you to book more, and then on the day you go, it turns out that the test is not in place, you'll be stuck using your FPs for a time when you least needed them. Or, you might try to change them to the afternoon/evening only to find out that the times are all gone for the popular attractions. So personally, I think the advantage still lies with those who arrive early, ride SB in the morning, use your FP+s in the afternoon/early evening, and if you get a fourth (or fifth) FP, good for you. And if you don't, you don't. But I would have to be pretty close to 100% certain that this test was going to be active during my visit before I banked my 3 FP+s for the morning hours.