There is a very fine line in HD that involves winning because of something vs. winning in spite of something.
I've seen many, many cases over the years of guys doing something that was clearly detrimental, but they were still successful. If you have talent, you can mess up quite a bit and still win consistently. Just because someone makes a Sweet 16 run playing a combo defense doesn't mean they got there because of the combo. They may have been a F4 team running one defense with better iq's.
That's not to say that running multiple defenses is always a mistake, because it's not, especially with players capping out in individual skills with a frequency that didn't exist previously. That said, if your players are still improving when they graduate, I would say that there is probably too much time being devoted to team practice.