I love WDW. We are currently AP holders and have been 3 times in the past 11 months and will go a 4th time in December. No trip is long enough in our opinion.
All of that said, realistically, if (when) we live in the Disney area, we won't be on vacation. It will be our regular life. We will need to do all of the same things that occupy our time today in NJ. I'll still be just as tired when I get home from work in the evening, not raring to go trek around a theme park.
So given the 9-5 job criteria in your hypothetical, I'd say we'd probably only go a couple of times per month.
HOWEVER, it is my hope that if and when we do move to the area, which we would love to do, I'd be able to cut back my work hours. If you change the scenario to perhaps a 20-hour work week, then my estimate of time spent at Disney would definitely go up, especially in the cooler months and the relative "off" seasons when the crowds aren't quite as bad.