Project Selection Process
Cal emphasizes the importance of distinguishing between deep efforts and support efforts when selecting projects. He suggests focusing intensely on two to four deep efforts at a time, while managing support activities separately to enhance productivity and maintain concentration.In this clip
From this podcast

Deep Questions with Cal Newport
Ep. 124: LISTENER CALLS: Preserving Depth in the Vast Shallows
Related Questions
Did Cal Newport suggest working on two or three projects maximum at the same time in the episode Dr. Cal Newport: How to Enhance Focus and Improve Productivity or the clip Deep Work Strategies?
What are Cal Newport's main pieces of advice on deep work and productivity?
What are Cal Newport's specific techniques for deep work?