I`ve always shot sitting from stands, tree and ground but keep reading where people mention standing to shoot. I just wondered why people stand up to shoot.
After a summer of shooting standing it is amazing how uncoorodinated I am am when I sit. they both need practise, after 12 attempts I finally hit a green tomato at 10 yards,yuck.
From a treestand some shots are just not possible while sitting.I do both depending on where and how the deer come in.If you have a longbow and are sitting a righted handed shooter would have a hard time shooting deer to the right or behind the tree.By standing those shots are do-able.
Ditto what James said
try sitting, cross legged, under a spruce tree with a 68" longbow at a buck at 5 yards. Sounds easy eh. The buck came in just off to the left slightly from my left to right. Perfect heart shot.
Every situation is different, the hard part is being in the position when the time comes. Try chasing caribou on the barren tundra once and you'll know what I mean. Standing isn't usually an option so shooting in odd positions is the norm.
When I'm in a tree stand I do alot of standing.The first thing is when I settle in to pick spots where can I draw back and get a arrow through actually draw your bow. I can shoot through there and there etc. The biggest reason I like standing is being a smaller silhoette[5-9 170] for deer to see. Standing back to tree versus a sitting blob in the tree. When I stand I'm always at the ready sharper when I sit I "drift off" some times. I do practice shooting both ways though because you never know.
I like to stand in a tree stand, and will shoot that way also. When I'm in a blind i like to shoot sitting or kneeling or a combo of both.