Arm Curl In Swim?

My swim coach, an accomplished competitive swimmer, wants me (not an accomplished competitive swimmer) to curl arm at the beginning of the catch. To the contrary, Terry Laughlin of Total Immersion specifically says not to do this - that it works for pros but not a good idea for mere mortals. See 7:35 minute mark of this TI video.

Do you curl? And would you recommend curling for the swim-challenged - versus flapped wrist as Terry recommends?

I would recommend not asking this question, or if you have to, ask it of the pace clock.

The reason I say this is to curl or not to curl is one of those small refinements that may be the difference between repeating 1:05s or 1:04s. The way you describe yourself, it sounds like you have better things to do than micro-manage the minutiae.