If you like standing in line watching those in the FP line go past you then sure, don't book them.
Personally, I book them no matter what. Even when they are totally unneeded, like with Nemo or Little Mermaid
Heck, for those 2 rides you save a lot of time walking through the empty queue. I'll stand outside of those rides and book a FP for that exact time just to shorten the walk/weave time.
In most rides you save at least 15 min in line. Heck, 3 rides and you've saved 45 min right there. Why spend 45 min more in line when you don't need to?
On several rides you'll save even more time. One thing is for sure, you'll never spend more time in the FP line than you would stand by.
A very common misconception is you need to book them well in advance. Some you do. Mine Train and FEA are quite hard to get last minute. Pretty much every other ride is not. You can book them that day, or maybe the day before, when you decide what park to visit. Trust me when I say you'll be slowing down the 4 yo to go at your pace vs. you slowing down to his pace

Don't worry about you controlling some of the time frame for the day.