This question has been debated before with some suggesting no pro would shoot without two cards. I can understand the peace of mind it brings, but with the new Sony A7III's, I've read that the camera locks up if one card fails, so the camera is useless regardless of having two slots. I also think that CF cards are becoming more obsolete now with XQD and high capacity SD. Pins in camera for CF seem prone to damage too. I've been shooting with a Nikon D810 because I love the OVF, but have been thinking about my once owned Sony A7RII after going over a few ski photos. That camera was amazingly light with almost MFD quality and can now be purchased brand new for the price of an Fuji XT3. So, I'm curious about other experiences with CF, SD or XQD. There's considerable feedback from photographers in favor of two, so why did Nikon's Z leave them out when it's certain a new model will have two? Are two cards just marketing hype or camera makers known practice (Leica) of leaving out useful features only to be used in the next iteration of cameras?