Probably don’t really need it, just makes it easier. I tried it with some potato class models first and they would ignore or mishandle constraints, especially when vaguely worded. Sometimes it would try to send us to events that were obviously in the middle of the school day, and I’d look at their reasoning traces and there’d be some really boneheaded mistakes in there. If it reliably sends you a decent fraction of garbage reccs, the emails stop getting opened, my SO has no patience for that.