The family that drinks coffee together stays together. The Mason show's famous coffee-cup rack symbolized the cast's togetherness. The cast and crew hung out and hung tough together. The set had a built-in kaffeeklatsch nook, a cupboard containing ceramic mugs for each member of the cast and crew. It was Burr's idea, as an example of not just the show's longevity, but also its permanency.
Most series celebrate when a season's worth of episodes are complete.
Tradition calls for the stars of the show to ante up money for the season wrap-up party. The Mason series crew would have a party at the end of filming of each episode, with Burr and Gail Jackson splitting the cost. Happiness can breed complacency. And apparently Burr was the ringleader of all these positive vibes. And this can backfire.