Oh no no, you definitely don't want to leave a single ring in for 3 months. It doesn't have enough hormones in it to protect you from pregnancy for that long. It is possible to have only 3 periods a year on the ring, but you still need to insert a new ring once a month, whether you go for 3 or 4 weeks. Its just a question of inserting a new one right after removing the old one- then you have no withdrawal week so you skip your period. It works well for some people, but others do have spotting, as I mentioned. I've never had spotting when stacking the ring, personally. It has a low dose of hormones, so a lot of women have luck with skipping periods entirely :)