Or taking 4 academic courses vs working on 4 different projects.
There are many differences between Academic and Entrepreneurship regarding works.
Academic-wise, it is advised to migrate between subjects such that you correlate and review them from one another. For example, Physic could use a problem originated from P.E as an example to strengthen Physic concept. Math could use Chemistry concept but with a focus on how the number works instead.
Furthermore, there’s always handy syllabuses.
In short, Academic were designed such that one can multi-tasking between disciplines.
Working on projects however, it is better to be more focused on the current project. Customers do prefer a steady and planned schedule. However, project need more focus and determination than academic course. You cannot mix two project as one. You cannot multi-tasking.
Project were designed such that one must focus on each of them, and try to finish something rather than looking at all of them at once.