I usually have a Spyderco PM2 in my pocket as well as my Leatherman Surge on my belt.
I use the Surge blade for cutting stuff that is very dirty, dusty or gritty, it also gets used as a gasket scraper at times, paint scraper, poking and prodding other grungy gritty things. Cutting sand and dust covered rubber hoses for example.
Not so much things I shouldn't use a knife for, but my multi-tool saves wear and tear on my other knife, so it stays keen and sharp when I need to make clean or precise cuts.
My multi-tool blades get a quick sharpening with whatever is available, usually something in my toolbox, mold stones, armature stones, a piece of emery paper, just quick and dirty utility edge. My main pocket knife doesn't get a polished edge or anything real fancy, but much more refined than a piece of 220 grit sandpaper.
Basically two different tool used for different jobs.
I will occasionally use a utility knife if I have to cut up against a piece of metal or something, but utility knife blade quality has dropped off so bad over the years that I always end up honing or deburring them before I can use them anyway.