Yes, but that doesn't help the person who has 'let the tank go' and is trying to re-set it rather than tear it all down and start from scratch. But your point is well taken.
I'd be curious to know whether most of the people who did this protocol and didn't experience widespread livestock death had 'relatively' larger tanks.
Look I'm not saying this can't help some people, but yeah the size of tank will play a factor as well as a bunch of other variables including everything from livestock, light, experience, dedication the list goes on, on. There's no control. It's just another eye-opener to get your house in order from the start. Excel alone is a dangerous product especially in small tanks, so many people don't realize they overdose way too much.