I'm not a chemist - but I've got quite a bit of experience under my belt. I've cycled tanks using discus before by using the consistent water change method. I was taught by several discus breeders that if you do large daily water changes - 80%+ it will speed up your cycle and it's true.
I've gotten a 100 gallon to cycle in 2 weeks time using 12 discus...
I'm not sure where the opinion that you need to leave the same water in a tank for it to cycle comes from, but I don't think it's true.
Just my two cents - go by what you know to work. Water chemistry is an odd thing and just because it works for me doesn't mean it will work for you.