I used to think that about copper, but after fish leaping out in TTM, velvet becoming as common or more common than ich (TTM doesn't address it or Brook), and the Hanna Copper Checker "discovery" by
@HotRocks, I've opted only for Copper thus far.
CP is a promising alternative if you can access a pure form of it, which is challenging for most of us without a script from a veterinarian (mine require me to drag fish in for an examination prior --- they wouldn't know what they're looking at anyway and that's a lot of stress on a velvet-afflicted fish, or even a healthy fish for that matter!) The Chloroquine Phosphate source on ebay has some QC concerns, not sure of the purity.
Copper Power, Hanna Copper Checker, General Cure (in lieu of prazi due to the fact it's effective with a greater number of flukes and worms), and some bacteria in a bottle is my go-to!