The rishing and falling water brings in new fish, and causes present fish to move around, increasing chances on your fly swinging past a fish willing to take it. That's good.
The weed is also good - good for the ecosystem, the insects, cover for the fish and so on - it needs to be there. But - I can still throw a curse or two after it when I get snags and hook-ups on every other cast. So I do what I can to minimise the problem.
Fishing a traditional double is catastrophic. Two downturned hookpoints seem to attract every single piece of drifting weed in the river. Add to that that we're fishing dense sinking lines, which makes it hard to avoid the ever present weed close to the banks, and you're guaranteed a snag on every single cast. So - while I love tying on tradtional doubles, and I love fishing them, I just don't use them during summer and fall (in Denmark, at least).
A treble is even worse, but I very rarely use trebles anyway, so that doesn't really bother me.
A tube fly with an upturned double is a good solution. It doesn't catch too much drifting weed, but does tend to snag more on the bank than a single.
You can't really turn a single up into the wing, since it's foul quite often, but you can of course fish a single tube hook, turned down the normal way. That definitely causes less trouble on the "bank weeds", but does catch drifting weed now and then. I use the Ahrex Home Run-series, where I can get both trebles, doubles and singles (the latter both with and without barbs).
But - there's a catch, or - maybe not a catch, actually. I don't have numbers, but I clearly loose/miss more fish on singles than I do on doubles. Both as they strike, but also after what seems like to be a good, solid hook-up. And the strange thing is, that often on the doubles hooks, only one hook has (properly) connected, so why the difference?
I don't know, but I have a theory that sometimes (maybe often?) a hook will not penetrate properly right away and might shift once or twice before it sinks in properly. And if that happens there's just a greater chance (from a fish pont of view, risc seen fro m our end of the rod) that the hook slips out if it's a single.
Even so, I choose a hook that gives me the least amount of snags when fishing.
Have a great weekend!