I was wondering do most people have balls that they only use for tournaments and others balls used primarily for league ?

I don't really bowl tournaments but i have a sport league and a house league.

I bring 4 balls to sport and 3 to league, except i almost exclusively use 1 ball for league but my shoes and what not are in the 3 ball bag...

I definitely have equipment that only goes to tournaments.  In league, I take a spare ball, and mostly just whatever ball I feel like throwing.  Lately, I've been taking 2.  I forgot that sometimes the ball returns and stuff can eat your equipment, so I like to have a back-up.

Once I find a ball which I really like, I try to save it exclusively for challenge league and tournaments.  I try to use equipment which I am less comfortable with or find myself throwing less often in practice and on our house shot.  This is situational and there is no reason why given the right lane surface or shot that a ball which I use primarily in practice can't make my tournament bag.