I'd say more than a metric ton. I nearly wrecked my shoulder. Between trying to bareshaft tune, and bad form.
Recently getting back into the swing of things, I found stu's calculator. It saved me alot of headache, and allowed me to work on building strength to achieve proper form. This time around my form is is good enough so I can confirm the spines I come up with on the calculator.
I should make it clear that ALL measuements fo bow weight, center cut, draw length etc... must be accurately figured out to get quality results.
Good luck.
Brian