Dude I was on one of those episodes and Kevin Smith is being kinda humble about it. We would wrap on a shooting day in half what it could have been on a worse run set(which is VERY common for a CW show) and a decent part of that is that Kevin Smith trusts the crew to do their job even in cases where he can't directly be present.

In fact, I was there for one if the "without him" scenes and its basically the only times I've ever seen a director willing to let the crew do things so autonomously, and the camera and stunt teams had a blast getting the scene done at the time.

It doesn't sound like a lot but this is definitley a skill that he's developed and an extension of his fairly unique philosophy to filmmaking.