I often struggle to find OH space because I always book a rear seat and Airlines still think it makes sense to board economy front to rear, creating massive logjams as people try to put their stuff up and sit with people trying to move past. It’s not the fault of the passengers; it’s a slow and inefficient process due to this ridiculous front seats first policy. Having said that, I,ve been on a lot of flights in the USA where the flight is full and the airline suggests (in some cases insists) that roller bags are tagged and placed in the hold with checked bags, for free. Unfortunately his encourages people to not check a bag, but to jam their stuff into the biggest allowable carry on bag. So if the free checking doesn’t occur, there’s a lot of stuff going in the cabin, and not much room.