I can't speak for everyone, but based on my experience, regularly drinking (even lightly) during the day would be likely to cause significant productivity loss. Duh?
Of course there is a line to walk between a couple of beer and the three martini lunch.
That is true for productivity but what about your health? I like drinking as much as the next guy but drinking a couple of beers every day, at work, just to "relax" and "focus better" seems like a bad tactic.
[1] http://www2.potsdam.edu/hansondj/HealthIssues/1106591095.htm...
If you moderately drink at work and then drink outside of work, does that count as moderate consumption?