Tonk,
After LEARNING to use shooting sticks, I carry them when hunting anywhere, whether a small set for sitting in open country, or a taller, adjustable set that can be switched between sitting and standing heights.
They don't get used for every shot, because they're not needed for every shot. But with practice they can make a sitting shot as easy as prone, and just about double the effective range of a practiced offhand shooter. And yes, there are many places in North America where the vegetation prevents using a "natural" rest, just like in Africa.
My favorites are an adjustable 2-legged Bog-Pod, and set of Underwood sitting sticks I've had for at least 15 years. My wife, however, likes the 3-legged Bog-Pod for everything, and has made some spectacular shots off one.
