Well depends on what team you manage...if you manage a team like you did Real Sociedad a average team that has quite good facilities then its Obv 2 seasons or 3 will probably be enough to beat them. Also money helps..if you buy great potential players or good players that can beat Barcelona's team with a good tactic as well.
The real challenge is like what i done.. Turn a **** team into a super team and beat them. English league two team, Wycombe Wanderers, 4 seasons Promoted to EPL, matching top teams like Man Utd. 5th season..promoted to europe, beat teams like Barcelona, Real Madrid, Inter milan and on top of all win the cup. Now that is fantastic.