I think the hope is it will stop bleeds completely in the long run, but everyone is different.
Some people get a little bit of blood for a long time after first getting it fitted, I was told for up to six months! Saying that, I had mine fitted in November and the bleeding was only really worth mentioning for the first few weeks, after that it was just the smallest bit that went on and on (not even enough to need a pad or a tampon, just enough for something to be there, if that makes sense). I stuck with it because it's working better for me than all the other progesterones I've tried so it felt like a minor inconvenience in comparison. A few weeks ago it finally stopped and I've had no blood at all since - hopefully that's all done now!