WOW.... Not an easy question. I think it depends on how much "natural" talent a person has..
I am a good speaker in front of people, so I don't have a problem with the "patter/banter"..
Since I only perform 3-4 times a year at church, and 5-7 times a year at family gatherings, I tend to use tricks that I can "re-practice" a couple days a head of time.
I just started using cards in my act (have been performing for over 30 years). However, the decks are self working versus having to do lifts, sleights, etc, etc.
So depening on your "abilities" and "difficulty" of the tricks you want to use, could/would dictate the amount of time you need to perfect your act.
I love watching card masters do card tricks, I just don't like to practice that type of magic... I did learn how to do one "difficult lift" which I can't remember the name, but if I'm at the computer on a conference call, I pick up a deck of cards and practice it...
cheers,
don