Our weekly game night has been on Mondays since...I don't even know. At least 5 or 6 years. The group is comprised of old friends who all like and respect each other. We understand that missing a game session, or canceling if you're the GM, is disruptive. But stuff still comes up. Kids get sick. Wives end up with commitments on the same night such that we need to be there with the kids. Vacations get scheduled.
The key for us is that a missed opportunity to game is not a missed opportunity for fun. We've got a LARGE set of boardgames that we can draw upon. We frequently fall back on Rock Band. And sometimes somebody will throw together a one-shot game they've been thinking about to fill the gap. It's all good.
Spending time hanging out with friends is never something I regret, even if we can't manage to play the game that we'd been planning on.