Building a shift schedule generator taught me that scheduling is harder than it looks

I recently built a small tool called Shift Schedule Maker. At first, I thought shift scheduling would be a fairly straightforward problem. You have employees. You have shifts. You assign people to shifts. That sounds like a simple table. But once I started building it, I realized scheduling is less like filling out a calendar and more like solving a constraint problem. A valid schedule is not necessarily a good schedule. For example, the system has to think about things like: Does every...