How many Permanganate treatments

I've finally gotten around to treating my GF tank with PP. I've put it off a
few times,as they always seemed to get better (Melafix, Salt, water
changes), but it never completely went away. This week Panfry's snout bump
was back larger than ever and he lost a couple more scales, plus the second
biggest fish had a couple of bloody scales. So I've been keeping their water
pristine all week and took all the plants out for the big day.

Last night I treated the whole tank with 3 PPM to start (light purple) and
added 1 PPM every couple of hours to keep it pink/purple for six hours. I
disconnected one of the filters and left one running. I'll reverse the
filters for their second treatment. I originally had concerns about harming
the fish and/or killing the Biofilter, but they seemed much more energetic
this morning. Not that they were laying around before. They were a little
freaked by the purple water, but took the whole process in stride. I wish
I'd done this sooner.

The bump on Panfry's snout did not seem much different this morning, perhaps
a little less fuzzy and slightly less pronounced. But tonight the white spot
has broken completely open and the skin is hanging loose. It took a week of
Melafix to produce this result last time and I found I could get the same
result with daily water changes. So tomorrow they get their second treatment
after a water change today.

But how many treatments should I give them? I've read about giving them up
to four treatments two days apart. But if they don't need it. I realise this
will depend on the results, but based on tonight's results, one more
treatment might do it. Although I don't want it coming back either.