I vote for 1 week.
or be like jim_0068 who says he can go from hitting on one swing to swinging on another AND then goose it up to 4 barrels as well.
I can do some of this too, but tend to switch to a procedure and keep with it for a month or so before something starts getting lazy and I need to find a correction and morph to a slightly different (or way different) procedure. So once the lazy thing is noticed, then I will work on making adjustments over a week. And actually, I can often find the correction right away and then just need a little bit of time to ingrain the new pattern to be able to do it thoughtlessly.
I think if whole new views of what you are doing are involved, THEN more time is needed to program the brain to accept the new viewpoints as legit.