Originally Posted by flyingnosh

I don't have a lot of data points as I don't travel much internationally, but it seems to me that it makes a difference whether the passport details are stored in my profile. If I just book a flight, enter the details during booking, then fly, then book another flight the same way, then the second time I need to show my passport again during check-in. But if my details are in my profile, and I booked tickets that way, then I'm good to go the second time. It might have just been coincidence, but I suppose it wouldn't hurt to just have the details in your profile before you book a flight.