There is not much info on slip stroke and apparently no clear definition. From what I have read I believe I do utilize the slip stroke when I get going, kind of in the zone. I have tried to force myself to use it, to push me in the zone and it seldom works. The slip does not push me in the zone, the zone itself creates the slip stroke in me. That is me, perhaps different to others who use it, I am new to it, but like it. I only use it on normal shots, not over the ball stuff etc.
This is how I characterize my slip stroke. When I am there, I am very loose, kind of fluid like, natural. I know it sound dorky, but it the best way I can think of to characterize it. During the first two strokes the butt slips around in my hand by about an inch or two searching for the proper balance point for that particular reach on that stroke. It settles down in about two strokes and feels good, straightens out etc. Then on the contact stroke the shaft will actually slide forward a bit (not always) about ¼ to ½ inch. The fact that the shaft is semi airborne there should be no side movement and follow through is perfect. Its just a nice feeling.
If anyone is a target bow shooter, its similar to not gripping your bow. You have a strap on the bow that your hand fits into so when the arrow is release the bow falls forward on it own allowing for a smooth departure of the arrow, no side twisting.