professional photographers often carry a very different kit to what I describe, I just don't know how they get it on the flights, for example, Steve Davey wrote an article
here and describes how he takes 2 Nikon cameras, Nikon pro-zooms: 14-24mm, 17-35mm, 24-70mm and 70-200mm, 10.5mm fisheye, 50mm f/1.8, 60mm macro, 300mm f/4, 1.4x and 2x teleconverters, Lastolite reflector, flash, laptop, etc and stuffs much of it in a Domke photographers vest which he wears at check-in to try to avoid scrutiny for excess carry-on luggage weight. I am sure most of us do not want that hastle, and transporting it in stowed luggage runs a big risk of theft or loss.