I have never done long haul, but feedback from friends who have done it would strongly suggest that it potentially shortens one's life span.
Maybe... 5+ europe - eastern seaboard with 2 pilots in one month is cream crackering. OTOH 3 - 4 trips with a day off down route and an augmented crew can leave you in a very different (and more healthy) state.
Mind you the new EASA rules may well change all that - for the worse.