I find it to be a little time/attention consuming to be constantly refreshing for any desired 4th, 5th, etc. FPs while in the park. Having someone “back home” searching for, and booking them allows the park goers to enjoy their time that much more. As Hiro said, it can also feel like you have your own personal concierge service guiding you through the park!
.......It can also be fun for the person back home that’s doing the booking too! Gives you the feeling you’re along for the ride. Even if only for a second or two.