Hi All, when do you stop sterilising milk bottles for your LO?

I stopped only when my boy wean off totally from his milk bottle, which was around 4yo. The sterilizer was there and it's not taking up alot of my kitchen space. So I just continue to do it even though I know it wasn't really necessary. I find that after sterilizing, it helps to clean the teats much better as compared to just normal wash.