I'd say I hand hold 99% of the time.
I shoot with with a Sigma 50-500mm, and a Sigma 70-200mm (sometimes with 2x plonked on). The main reason I shoot hand held, is that I simply feel more comfortable that way. I've always found a monopod restrictive. For me personally it make tracking a lot harder and it doesn't really add any benifits for me, unless it's very windy.
When I start shooting with the really big lenses, I guess I'll have to get used to one, but for now, hand held for me.

