The biggest things I’ve probably learned working on side projects are patience and planning. Side projects are a great place to hone your skills of negotiation with other people, but I’ve personally learned a great deal about the process of architecture, simply by doing side projects where I’ve experienced scoping and tooling problems later on. Being patient lends itself to getting better at planning. Working with others on side projects has given me insight into “when to hold em and when to fold em”...and again, this patience education has often helped me be a better planner for a multitude of tasks.