When I set my fictional league live, I plan to play "God" and adjust the parameters as time goes, and let all the teams play themselves without my micromanaging interference. So I will likely sim the whole season at once. To me, the fun will be changing the parameters from season to season and viewing/reacting to/reporting on the results, letting the chips fall where they may.
Of course, if "God" sees something goofy happening--like one team winning 10 championships in a row, or another team getting relentlessly smoked for a decade or so--"He" may do something to shake things up for them.
