I can usually go about 3 or 4 days without shaving before people start squinting at me and asking "Are you trying to grow a mustache?" 3 or 4 weeks and I look like the older brother in "Napoleon Dynamite". No matter how long I leave it, I get all the scruffbag and none of the macho. Reluctantly then, I shave fairly regularly even on tour. I'm not a fan of Bic disposables though so carry my Merkel and shave in the shower, which tends to happen in the evenings.
Then I change into my tux and prepare a martini. I'm not a barbarian after all.