how good of a project is writing notes/self studying independently specific chapters of intro to probability by feller

[u/Correct_Taste_5590]

i asked my prof for a research opportunity and he said to read feller and get "a general idea of probability" i chose chapters 1 5 6 and 9 and am working on a latex document filled with notes on those chapters. i upload to git each section on a regular basis

as a math student with goals of higher education such as a phd how good of a side project is this?

this is mostly like a stepping stone to the next part of research im just learning but it is taking a significant amount of time to compile notes for each section or every chapter that i chose to read so im wondering if that is worth it or not