yes and no. The best way to think of it is - even if the nutritional impact, or lack thereof, from a 6-8 hour binge on a sat. night isn't all that bad in the big scheme of things; chances are the next 1-2 days you're not giving your workouts everything you've got, if you even make it to work out the next day in the first place.
If you spend every Sat. night at the bar, then every Sun on the couch recovering, that's another 52 workouts you would have had that year. I don't know about you but I think there's a lot of room for progress over 52 workouts.