Commuting distance recommendations

Hey everyone!

I've been loving my eBike for getting around town, and I'm starting to eye it for my daily commute. My office is about 15 miles away, mostly flat with a few gentle hills, and I'm riding a Class 1 hardtail eMTB. I'm curious what kind of distances you all are comfortably tackling regularly on your eBikes for commuting? Any tips for longer rides, or at what point do you find the battery range or comfort becomes a real factor?