Draining has no rigorous meaning at all, and the reader can interpret it however they damn well feel like.
I am sure that the vast majority of people have had at least one day where social duties overwhelmed them. Extroverts, meaning people who are never ever drained by social interaction (for whichever meaning drained is given) seem to be vanishingly rare.
It may mean having to go to bed very early because you're all used up. The effects varies alot though.
It's not a preference.