I never "wear" one, but I almost always carry one to deploy only if needed.
I am mostly an ocean boat or shore diver. For ocean dives (including wrecks) I never wear it on my mask. I stow a foldable one with a "dry" top in a pocket, or strap it my harness. I do this in case of an emergency (ie separated from the boat at the end of the dive -- never happened so far). Even if I just have to wait a little while for pick-up, if it is choppy/rough I would much rather breathe through a "dry" snorkel than try to float on my back struggling not to inhale the water that is splashing on me. If the dive is in calm water, though, I won't deploy it because my usual preference it to float on my back so I can talk to my buddy.
Right now, I like the oceanic foldable "dry" snorkel because it has an oval tube that is much flatter than a standard round tube, and is therefore easy to just slide under your mask strap -- very simple to deploy. It also has a handy clip that allows quick attachment/detachment. I leave that clip on my mask strap in case I want a more solid attachment than just sliding it under the strap.
I do not use this snorkel for freediving. My needs are different for that (I want a larger bore, and don't need the "dry" top).
Like some others here, between tank dives I always have my mask, fins and the snorkel ready to go instantly in case dolphins, whales, sharks or other critters swim near the boat. I can jump in in about 10 seconds.
If I am shore diving and it is a long swim, I also use it to swim out/back on the surface, and detach it and stow it during the dive.