I just bought Game Dev Story, and I've made a few games. Each time, I assign the developer with the best relevant stat to each task. For example, I always use the developer with the highest Scenario stat to write the proposal, the one with the highest Sound stat to do the music, etc.
However, around my third or fourth game, these people started saying "I'm doing the ____ again? I'm not sure I can give this one my best..."
Does this mean that assigning them to the same job each time causes them to lose effectiveness? Should I be occasionally hiring outside consultants or using new hires?