Quoting Commander Shepard:" There seems to be a bit of confusion. If I didn't want her to have it, I would have taken it. I know ... [snip!] ... taken it. I know she is attached and needs him. All I was asking is when do kids usually stop needing their comfort objects."
For my son, he only sleeps with it now and no longer carries it around with him all of the time. He's just about 5. I'm guessing within the next couple of years, Yucky will be retiring.
But whenever he gets really upset, he still runs and gets Yucky.