Yes, absolutely. Due to the large number of side projects I've worked on over the years, it's very important to me that I can put something down and pick it up

Yes, absolutely. Due to the large number of side projects I've worked on over the years, it's very important to me that I can put something down and pick it up again later. Unit tests allow me to do that. They drastically reduce the amount of certainty I have that modifying or adding a new feature to an old code-base won't break everything.