For me it is about selecting the right tool for the job; 35mm, MF, LF, digital.
I was recently on a LF outing. The 4x5 monorail + tripod was TOO HEAVY to lug around, I was exhausted before the end of the day, and because I was tired, I did not shoot as much as I would have. And being middle-age does not help. I cannot lug around what I used to easily lug around when I was younger. So next time, if it will be significant walking distance from the car, unless I have a cart/wagon, I'm taking the MF and NOT the LF camera. My 4x5 is now restricted to the home studio or a reasonably short distance from the car.
A MF 6x6 or 6x9 would be my idea of a the biggest camera that I would walk about with.