You go into examiner interviews not knowing how receptive your examiner is likely to be to a particular argument or course of action.
You find yourself fishing for the right argument to use when you get hit with a nasty Alice or Mayo rejection.
The hours you spend supervising junior attorneys preparing OA responses are giving you a headache and cutting into your own billable hours.
Develop strategies for prosecution
Research how examiners responded to past arguments
Discover new arguments or find precedents to reinforce existing arguments