i wouldnt do that although it might be a little faster. u will get frustrated later on as you will only be able to manage prem clubs. what if you get sacked???
also there arent as many players available to buy.
i usually choose about 4 nations (england, spain, italy then either germany, holland, france or scotland) with default leagues.
i does depend on computer speed but i would always choose at least 2 nations with default leagues in at least 1 of them and top league in other no matter what. it's not worth playing otherwise.