underwaters are highly personal.
some can do them with ease and others cannot.
my only recommendation is do what you are comfortable doing and dont take stupid risks. (and by you i mean the swimming community).
dont push others to try and make it if they simply cannot.
even on breath control sets. do what you can do and dont push others.
as an example, i can make 25s pretty easy (thanks mark and those firestone 500s we did in the dive tank) and breath sets have no issue taking 1 breath for a 50. one guy on my team, we'll call him tom, cannot do that. so even though the written set says take only 3. i take just 1 and he gets my extra 2. i am safe and tom is safe. both doing what we can safely do.
p.s. and yes i have pushed myself in the past (and also as a masters) on how far i can go. but ive never thought i was in danger. however i wasnt so stupid to think i could make it past the turn at the 75 all under either!