Good morning Patrick,
This is a great question. We absolutely encourage artists to keep sketching, doing portraiture, landscape studies, etc…—whatever you enjoy doing. There is no reason to halt any of it unless you suspect that some aspect of the extracurricular activity is reinforcing a problematic practice or is potentially diminishing progress.
We have a number of “enhancer” resources available as well (supplemental material) that dovetails with the curriculum. These include:
Digitally enhanced Bargue works to supplement Shape Replication exercises:
https://www.smartermarx.com/t/shape-replication-exercises/80
And portrait sketch/Notan exercises:
https://www.smartermarx.com/t/portrait-notan-exercises/437
Please feel free to share any of your extracurricular exercises here on Smartermarx as well. I know for a fact that many love to see others’ endeavors here.