[dan-k]

Not interfering at bad times is part of the quality of interaction that you can tip on. Furthermore, how fast he brings the food out is far more dependent on the kitchen staff than him, so penalizing him for it doesn't make any sense.

[DrJ]

one could also say that a good server would come by and inform you that the your meal is taking a little longer then usual to cook because of some reason. If I am told that, I know that the server is at least trying. If the server is just absent for 30 minutes, then we have a problem.