White Spot Outbreak

The speed of the whitespot lifecycle is temperature dependent. The warmer the water, the faster they fall off. That's the reason the articles don't give a time scale. If you turn your heater up slowly to get the water to around 30 deg, that is the usual recommended temp. You rams will like it that warm! Turn it back down slowly afterwards. If your heater is like mine (the temp on the dial doesn't give that temp) make a note of the setting before turning it up.
Sometimes the parasites attach to the fish's gills. This is what can kill fish.

If you kill all the parasites in the tank now, it shouldn't return. The tales of it coming back are usually when the person has failed to treat the tank properly, and stopped the med once the spots have gone. I usually add two or three extra doses on the end of the course, but I do use it at half dose in the tank with the loaches.
But, should you ever introduce new fish that are already infected you'll get another outbreak. The parasite is invisible when it first attaches, we can only see it once its coating gets big enough. Fish that don't show signs in the shop could be in the early stages. This is one reason to quarantine all new fish for at least two weeks. I've has whitespot several times, which is why I now quarantine new fish.

Lost both Rams  But all Dwarf Rainbows (and both Otto's who somehow don't seem to have been infected) seem much better. It's day five since I spotted the infection and commenced treatment but the Rainbows still have some spots (albeit many less). Is this normal when five days into a seven day treatment? Could it be they are not spots at all but the marks left behind when the parasites dropped off?

Sorry to hear about the white spot trouble and the loss of your fish Wild Rover. I had an outbreak 2 weeks ago which unfortunately plagued 8 of my fish who died because of it. My last treatment was today, so after today I'm going to be keeping a close eye on the remaining fish that's left whilst keeping the temperature up until the 25th, then lower it from there.

Such a stressful and frustrating parasite. I'll be restocking my tank in the new year with a whole new stock