With the prominent leagues, there is definitely a balance. Players are largely placed via dialog and/or relationship between the college coach and the Summer League organization so there is a general agreement or expectation of reasonable playing time for those players. So, the summer league coach must try to balance pleasing the organization by winning and pleasing the college coach by fulfilling that playing time expectation.
Of course, with some of the mid to lower level leagues that charge player fees, there is generally an expectation to play because the player is paying.