How can any respectable tog go and do a portrait, event or wedding using a camera with a single memory card? Frightening...
I guess in the film era no photographer was respectable enough, to think that you are limited to a 24 exposure roll and then you have to wind it and change the film, the horror...
I shot wedding in the film era, a wedding consisted of 2 rolls of 24 or 36, and it was accepted that due to a number of factors, the pictures may not actually turn out. Wedding togs were employed to make sure pics were correctly exposed and in focus - with a few nice touches along the way. And more over, they just covered the wedding so may have shot 3 or 4 weddings in one day!
Today, pictures being in focus and exposed correctly is not enough. Half closed eyes or embarrassing pose is not acceptable. The tog tends to cover most of the event from B&G getting ready right through to the end of the reception. 'Special' shots are almost expected. Video seems to be becoming the norm as well.
And on top of this - not having images to deliver because the camera, lenses or memory card failed is not acceptable. Redundancy across the line with kit seems to be the way forward. If Nikon can put in just about all of their cameras - why aren't Canon?
I don't do weddings because i have a single 5D2 and it only holds a single CF card. I would not be able to live with myself knowing i did not have the redundancy in kit when shooting a wedding and ruined some ones wedding day through failure to deliver pictures...