Playing to your strength or overcoming your weakness: the role of effort substitutability in skill formation

This paper studies the allocation of a given time budget among a number of skill-building efforts to maximize an overall skill level. The main finding is that as an effort becomes relatively more effective, the time share of the effort should increase and the time shares of the other efforts should decrease (i.e., one should adopt the strategy of playing to your strength) if the elasticity of substitution is larger than one. However, the exact opposite is true (i.e., one should adopt the strategy of overcoming your weakness) if the elasticity of substitution is smaller than one.