Good question, actually both. Adjust cast angle and mend to get the nymph down, dead drift, and usually feed line at the end of the drift if there is strong current or depth. Then tighten up so fly rises and swings. About 60-80% of the fish will hit when the fly starts to rise but they also take on the dead drift. Caught several fish in the chop at the top of chutes on the dead drift this year. And BTW using floating line but not using an indicator.