How Many Irons Can You Have in the Fire?

Anyone here with multiple irons in the fire who is satisfied with both the quality of their work and their income from it? I am trying to answer some hard questions for myself in this regard and hoping that examples will help.

EDIT: Or, alternately, people who failed at this and want to tell their story of how focusing on one thing worked. Pros and cons can be equally good food for thought.

Thanks.