I use one all the time, whether or not I put it into play for the shot. It's basically a shoulder-high walking stick and invaluable in our rugged terrain. But when the grass is tall (usually) there's nothing like it for steadying an offhand shot. Seated as you propose, or kneeling, it's even better. I can get derned close to benchrest accuracy with my butt on the ground, elbows on knees and the forend rested on the hand holding the stick at just the right height. I've found it best to wrap my fingers around the stick, hold my thumb out, and rest the forend between thumb and stick. For best results, don't squeeze them together. If you want to get REALLY steady, it doesn't hurt to have a pointy end on your stick, and to shove that into the ground before resting for a shot.
Works so well for me, I just can't bring myself to carry yet another stick for official "crossed sticks" a lotta guys swear by.