About 7 years ago, I attended a workshop by the photographer Howard Bond. He works mostly with 8x10 and 5x7 but had a few prints from 4x5 and a few 11x14 contact prints. At the time I was using 4x5 almost exclusively. The prints he showed were mostly 11x14 and 16x20. There may have been a few 20x24 prints but nothing larger. I had a hard time seeing any consistant difference in quality between the prints from 5x7 and 4x5 but could reliably pick out which prints were from 8x10 negatives (I also could not reliably see a difference between 11x14 prints from 8x10 and 11x14 contact prints, but that's a different issue--I actually prefer 8x10 "enlargements" from 8x10 negatives to 8x10 contact prints they look a little sharper, but that's just me).
Anyway, from that workshop experience, I decided I wanted to work with an 8x10. I eventually found a used 8x10 enlarger and bought an 8x10 camera. I mostly stopped using the 4x5 unless I was going on a trip by plane. At the time, I could easily see the difference in my prints from 8x10 and 4x5 negatives. My output in number of good negatives per year dropped dramatically. Carrying the camera and especially the film was a great burden. Going from basicly unlimited 4x5 film in readyloads to a very full backpack with only 10 sheets of 8x10 film made me more careful with every exposure and kept me much closer to the car. When looking at negatives and prints, I kept thinking that shooting more variations on each subject would have given me better results. When showing prints in galleries or friends and customers, I could see the difference between 8x10 and 4x5, but no one else could.
After a 3 or 4 years with the 8x10, I bought a 6x7 Bronica SLR to loosen up my photographs. I generally would expose 4 rolls (40 exposures) with the 6x7 to every 4 sheets I'd expose of the same subject and time. The content of my photographs improved dramatically from ease of use and exposing much more film. Content differences are way more important than any subtle differences between 6x7, 4x5, 5x7 or 8x10). Friends and clients still can't see any differences in my prints, although I rarely print larger than 16x20 (and I do usually use Pan F in 120 vs Tmax 400 in 8x10). Larger prints are generally looked at from further away so don't need to be quite as sharp (too me a long time to get over this!).
I eventually got a 6x9 Horseman view camera to get movements, but still usually use the 6x7 SLR for speed. The 4x5 has sat in a case unused for several years and the 8x10 comes out only rarely. I learned a lot from using the big camera and don't regret it at all.