The exception that proves the rule
But yeah you're right there will be the odd 'what if' anomalies like that if you play honour off the tee (remember they would also have to be last to putt as well for this to be true otherwise they should already be retrieving their bag) but again its not adding 30/60 minutes to a round
Just frustrating when its voiced as a primary reason of slow play
not necessarily last to putt and who walks of to get there bag if the others are still playing?? i see this type of behavior all the time, it might not cause the round to take an hour longer as you suggest but it certainly leads to losing ground on the group in front so gaps appearing in the field.