What effect does playing a particular off/def have on improving IQ? I have seen mentioned in the forums before that OFF/DEF IQ grades are mostly a function of number of minutes practiced times practice cycles. When switching between offenses does it make sense to keep playing the old one that your players know or does switching immediately help speed up improvement?

There was an experiment done last year where a coach put zero minutes in offense and defensive sets and by the end of the year I think they got to like a D-, meaning very little growth from just playing the set.

General consensus is practice the set you want, but play what they know for the first year.  You'll get an email along the lines of "why are we practicing what we're not playing" from your assistant coach, but it doesn't matter.  Either way it's a year or two to change sets.  

Minutes in practice are what increases the knowledge, not so much time playing that set.

I always believed that playing a set helped, but that report in the forum was convincing

I also have long speculated that playing AGAINST a set helps IQ.  Otherwise, I cant explain the gradual growth of IQ in sets you neither play nor practice

It was the thread started by robot devil. Barely any growth in IQ without minutes practiced in the set.