Depends on a whole host of factors including:
How good your Comp / laptop is
How many leagues / players you load.
How long you take in researching players etc.
For instance - I have a pretty good computer, but sometimes like the insane level of detail that you get from having 11 leagues fully playable, and pretty much every player in the world loaded, even for the random nations like Indonesia etc. This type of game can take many hours of playing to complete one season.
Conversely, only load a few nations and only well known players, then the season can be completed much quicker.