Desire to serve and desire to serve 24/7 everyday are two very different things.
First question anyone needs to ask themselves: Is this *really* what I want, or am I just trying to live up to what may be an unrealistic idea?
This should be asked from both the sub and the Dom. Being a sub 24/7 isn't easy, but needing to 24/7 be the one in charge isn't everybody's cup of tea either. I think overall the idea is probably just that for probably 95%+ of D/s couples, an idea.
Personally, and not all agree with this (which is fine, th ecommunity has somethign for everyone), but for me vanilla existance some of the time just isn't that bad an idea. The Lifestyle is an augmentation of it for me, not an outright replacement.