I have the following lenses - 18-55 IS, 35mm f/2, 50mm f/1.8, 70-300 f/4-5.6, 24-105L.
I got the 24-105 as a kit with my 6D, and basically it has become almost the ONLY lens I use with my 6D. Just this weekend I used the 50mm just to change things up for change's sake, but I felt like I didn't need it over my 24-105.
Because of the ridiculous high ISO capability of the 6D (I get pictures I'm perfect happy with at 12800), I haven't found myself in a situation where I've needed anything faster than f/4. And at the longer end of the range, I find I get enough bokeh for pictures where I want subject isolation.
For the rare sports/ wildlife pictures I've taken, I just take my 60D with the 70-300.
I guess if Sony or Canon or someone came out with a camera like the RX1 with a zoom lens then I'd be in heaven.
But I'm wondering if by not experimenting with more lenses, I'm limiting my progress as a photographer? I'm constantly wanting to improve.