That's good to hear.
I've always just pushed it in, with my middle finger, as far as it will go. I've never measured it, but my middle finger measures about 7cm (about 3 inches), so I guess that's how far mine goes in.
I've never actually seen any intact pieces of the casing/tablet come out, but there is usually a small amount of white "speckles" in my first wee of the day.