Oh 100%. As the creator of a product, you're always going to find it easier to use than anyone else is.
And this makes sense, since it's the unfamiliarity of a product or service that is arguably responsible for 90% of the learning curve. When you know what all the menu commands do, or where every feature is located, you're going to be a lot more efficient (and a lot less frustrated) than someone going in blind.
It's especially noticeable for games, since the designer knows where every single enemy and obstacle is, and how every single area is laid out. But the players don't know this, and often get blindsided by things the designer thought was immediately obvious/trivial.
So yeah, while you need to use your own product, you definitely also need to have others try it out and give feedback too.
