The Fortnite phase hit and I'm not ready

My 10yo just discovered Fortnite through school friends and suddenly that's ALL he wants to talk about. I let him play for maybe 45 mins a day on weekends. The thing is... it's not a terrible game? He's not getting toxic, he's actually learning strategy and teamwork. But omg the DESIRE to play more is INTENSE. He asks constantly. Negotiates for more time. I'm holding the line but it's exhausting. Anyone else dealing with this right now? How long does the obsession phase last? 😅