PfcAJ
Contributor
5' hoses work well for open water, for people who are relatively slight in stature. If you are broad or deep chested, the hose may not be quite long enough to sit comfortably in your mouth without any tension.
GUE used to allow various hose lengths, from 40" in open water, to 5' or 7', depending on diver size and application. They did away with that a number of years ago, and all GUE classes require the 7' hose now. I don't know what UTD does.
A 40" hose is pretty slick for shallow reef type stuff. Seems to route better than a 5 ft.