Why do you need to find the bottom and adjust the drift in fishing Is it to find the bottom first or to adjust the drift afterward

Find the bottom after drifting. Drifting is to adjust the buoy to a certain number of eyes by cutting the lead skin, usually four to five eyes is more appropriate. When looking for the bottom, you can hang a larger bait ball on the hook, at this time the buoy will be pressed to a certain number of eyes underwater, for example, adjusted to five eyes, after adding bait may become one eye, this time to pull up the buoy, until after hanging the bait to reveal the number of eyes to become more than two eyes, this time the hook to the bottom