In my experience never felt comfortable and the pressure on the back of the ears meant I wasn't able to wear for an extended period.
I have the Sony WF-1000MX, they are larger than most wireless IEMs but I don't need to push them in further or tighter than a normal pair of IEMs to make sure they don't fall out.
They did take a bit of getting used to as I was worried they would fall out and down a drain. I can wear them for several hours now and forget I have them in.