Yep, I'm totally in agreement with a small tank off to the side to get a fish adjusted and eating well. I'm just not a fan of treating it for a disease if you know your main tank has it.
Of course if the fish you receive has lots of ich showing, by all means treat it to keep it alive. But if it looks 100% healthy, I wouldnt treat it for ich knowing that when it gets introduced to the display it is going to get ich.
It's a stupid argument anyway and I'm done with it, sorry I got involved

The best thing to do would be to not have ich in your main tank ever to start with