Re: Czech nymphing with 1 fly?
Well, its a combo of the method and the files themselves. The flies used for czech nymphing have lead bodies molded onto the hook and are quite heavy. One normal beadhead nymph likely wouldn't be heavy enough to get down deep in turbulent water on its own.
In situations like that, I would use a heavy bounce nymphing rig with only one fly on a dropper. The idea is that you have a short dropper off of the leader with an unweighted fly and shot out on the far end. Search " bounce nymphing" on this forum and you'll get tons of info.
Props to Larry Tullis for spreading the word on the marvelous technique.