While I am not as seasoned as the others, I have recently dealt with ICH with Cupramine and then put the next round of fish through TTM from the start with Prazi in the process. I would highly suggest being proactive rather than reactive in terms of disease. TTM is not as difficult as it may sound, and in fact is truly easy once you get a rhythm going for it.
If you can remove ICH through TTM from the equation from the start as well as flukes/internal parasite through PraziPro you will be in a much better position should something else come up.
Some will advocate for the place in QT for long periods and just monitor then treat when needed; however, there are some things that are very difficult to know are present. Fish can carry ICH but have immunity to the actual physical side effects; thus, TTM helps to ensure you aren't putting a fish harboring ICH in the display tank. A lot of people have mentioned flukes being pretty common lately as well.
It all comes down to what you are able to do time wise. Looking back though I can honestly say I spend less time and have a lot less stress doing the TTM vs treating with copper.
The PraziPro isn't as rough on the fish as some other meds which is why a lot of people are likely to use it regardless of knowing there is an issue present. It is also straight forward without the need to monitor levels in the water as some others are so it is less of a hassle as well.
Just what I have gathered but it is simply one of the many aspects of this hobby that you will find various approaches and you just need to decide what is best for you. Welcome to the hobby of endless material to read!
