Agreed in most cases. It is likely that the ED boost is greater if the college attaches greater importance to “level of applicant’s interest”, since ED is the highest possible expression of interest there is. However, if the college is a reach for the applicant, “level of applicant’s interest” is likely less important, since yield is higher among students for whom the college is a reach.
Beware, though, if a previous student at your high school has backed out of an ED agreement. Some colleges supposedly punish future students at the high school by putting the high school on an auto-reject list (even for non-ED applications).