I can't really speak on using a 1/64 oz because I never have and really don't ever see the need to. I mainly use a 1/16 oz. but if the fish are finiky and want a bait falling I will downsize to a 1/24 oz. first and on down to a 1/32 oz. if needed. Sometimes the fish will prefer a smaller bait and it pays off to downsize. If the fish are deep and it is windy I will try 1/8 oz. but a 1/16 oz is a what you need most of the time.
"It is better to remain silent and be thought a fool than to speak and remove all doubt." Abraham Lincoln