I have heard that it helps to include sets with a different breathing cadence in to a swim workout. For example alternate sets breathing every 3,5,7 strokes etc. I'm told this can help your breathing in the latter part of a longer distance swim leg. Has anyone any experience to share with this theory?
This sounds like a drill called "Lung Busters" The way it was explained to me is you perform them pyramid style. Start out breathing every 3rd stroke, then 5th, then 7th, 7th, 5th, 3rd to complete the set. I tried them and really didn't see any benefit to them. I'm sticking to breathing every 3rd stroke and its working fine.
I haven't tried the "lung busters" but I have tried the 5-3-5 and haven't seen a difference either. I breathe every 3rd strong on endurance workouts. On Interval workouts I do 3-2-3.