Maybe your child is really on the ball (or the school/counselor is), but my child’s idea of where she wanted to go and list of colleges really changed from spring of her junior year until now (mid-senior year). Even her desired major changed.
The more she talked to friends already in college, the more schools she visited, the more websites she visited and events she attended, the more her list morphed.
We did not do ED, both because she didn’t have a clear first-choice and because we also knew we wanted to compare merit aid offers. ED precludes that — it is take it or leave it.
She applied EA to half the schools on her list and that has been great (some of her schools didn’t offer EA or she was undecided about them until later in the process). First, she got those EA apps done before senior year activities got really busy. Second, she has received acceptances and merit offers and the chance to visit and learn more about half the schools on her list while waiting for RD decisions. It has helped her rank her choices.
Sometimes kids who need their senior year to bring up grades or enhance ECs are advised to not apply early, but that is a bit of a gray area as to how much advantage it provides.
Years back, our son knew exactly where he wanted to go from day one. He applied there and to one backup — both EA. He was accepted and thrilled to have it all taken care of by mid-December senior year … and then he ended up transferring his freshman year in college! 
Anyway, we approached it entirely in terms of the advantages or disadvantages to our kid’s decision making process, and not in terms of whether applying one way or another gave us an admissions edge. I think we thought if our kid is only going to get in if he/she applies ED, then it wasn’t meant to be, and tried to find a school that would love our kid regardless of whether the app was reviewed in the ED, EA, or RD rounds. It was complicated enough for us without adding that layer of strategizing for multiple schools, and nobody in our family had their heart set on a particular highly selective school.