depends on the woman and specific method. my mom didn't have a period for five years thanks to the shot, but she's never been prone to PMS or cramps or anything hormonal really. i have a friend with an IUD who spots occasionally but otherwise nothing. i have another friend with the same IUD who gets a period but it's short and easy.

i also had a friend who went on the pill and her period got 800x worse which is rare but it happens. so it's really a body chemistry thing