How and when do I determine to add weight to a wacky rig sanko? Does a fast fall produce more sticks.

Personally, I never add weight to a Senko.

Falcon

o really so you just give it a natural fall? No nail or nothing?

I never add a weight either. A weightless senko has a slow, tail wiggling fall that attracts lots of bass.

In this section (tackle), there are some topics up top that stay there the whole time.  Those are "stickies".  There is onew up there with a bunch of info about senkos.

I've been using jigheads up to 3/8 oz with excellent results.  I may be letting the cat out of the bag here, but it seems the bass have never seen this presentation.  I caught a 5lb 12oz smallie last fall using this technique.