That's what Stella does here, the early blooms are above the foliage but not the later ones. Maybe the foliage grows after the first flowers and then it obscures the later scapes, or maybe the later scapes are just shorter. I've never paid much attention because it doesn't put on much of a show later anyway. 'Happy Returns' does the same thing. One year I actually trimmed the foliage shorter on it so that the next round of flowers would show above the leaves, but it was a lot of work carefully cutting around the scapes and I never bothered again
There are big clumps of daylilies in this area that I know have not been divided in at least fifteen years and they still bloomed prolifically this year but I wouldn't say that applied to all daylilies under all conditions. One thing I would say is that the bigger a clump gets the harder it is to dig up, so one might want to divide before flowering decreases in that case.
