I said a while back that, of all the nations in this season's Champions League, England and Scotland are the only ones dumb enough to have two full cup competitions during a season: Spain, Italy, Germany, Holland, Russia, Ukraine, Switzerland, Turkey, Belgium, Denmark, Bulgaria and Poland only have one cup competition, while France and Portugal have a second cup competition but the top flight clubs get a bye into the later rounds - which is played when the league is having its winter break.
While a tiny minority of Premier League clubs are capable of competing on all fronts as they have the squads to do so, for the vast majority a cup run carries the risk of knackering your players or affecting the league form, as best exemplified by the season Middlesbrough were in two cup finals yet also got relegated from the Premier League.