A blank canvas presents endless possibilities.
You can experiment, test, depart from what you've done before, and try new techniques and arrangements.
Constraining the medium, always using the same tools to create, lets us focus on what we're creating rather than on how we make it.
If your canvas always looks the same—in my case, the same sketchbook, pens, brush, and watercolors—you can innovate on what you make rather than on how.
It's okay to innovate, from time to time, in how and what tools you use. New mediums lead to different creations.
But to reduce friction, stick the same configuration and focus on finding new ways of using it, face the blank canvas often enough to be in control of the medium.