Here is the skinny. No tank actually ever needs to be cycled if you are prepared to do water changes between daily and every other day. This is fine for short term needs but impossible to do when you have many tanks and over the longer term.
I have enough assorted cycled tanks to be able to move fish around and free up Q space. However I never have a cycled H tank. For one, many meds kill off the bacteria. Then there is the issue of having a disease you dont win against. You need to sterilize everything in the H tank, including the tank itself. Normally I do big bleaching on everything. But this means no bio can survive.
During treatment I do a 25% wc every other day. WC should be done before any daily dosing and if the change falls on a day that no meds are to be dosed, I will do a 25% dose to replace what the wc removes.
My typical H tank has a heater, thermometer, a sponge filter, a couple of rocks and a few plastic plants. All of it gets bleached before being reused. Sometimes this means replacing the sponge as these dont react well to being bleched.
If, by some chance, I cant free up Q space, I will set up a temporary uncycled something and follow the above wc regimin.