I follow the experts advice, your logic doesn't work for me.
It is quite likely that just hypo may eliminate Ick in 28 days, maybe sooner, however I would caution going to fast. I like to take the time it takes to make sure the fish are fully rid and more importantly, have been hungry and eating, time does not matter, it could be 21 days, it could be 30, eat fishes case is different, numbers are just guidelines. In my last save, an ocellaris clown, covered in Ick, was ready in 21 days. Ick started to disappear in 4 days, no spots in 8 days, and no reappearance up to 21, early, but was my decision, based on recovery, the fish is quite hardy and ate great! Some say 4 weeks after last spot gone, this is more safe!
The hypo method works on the parasite in a way in which they continually take on freshwater until they explode. Once this happens they should be dead, the TTM is a different thinking, not sure it changes things much.
As for the DT, it is reccomend by many hobbists and experts that Ick can be eradicated in 76 days without fish with an assurance at 99%.
The reoccurrence increases with each day you go quicker. I did it in 60, and lucky, it did not reoccur. But that's just cause I did not know of the 76 day fishless rule or I would have waited.
So it's really up to you, blaze a new trail or go with the tried and true method and time.