I don't think most adults are mature, so I wouldn't call it ordinary. But it is still 100% being honest all the time. You still have a filter, but you're being honest about all the emotions you're feeling and what is motivating you to do any given thing. You can work to start to remove the filter too, this is called self-actualization. That's something different.
I think you need to be 100% honest with yourself before you start removing your filter or it won't work and you'll end up throwing out the baby with the bathwater. 100% honesty is as much about knowing yourself as it is about not misleading others. Only once you understand yourself and your motivations can you start to experiment with just saying stuff that's on your mind without thinking about it first. The things you say will clue you in on deeper motivations that you can then work on being honest with yourself about.
I think you need to be 100% honest with yourself before you start removing your filter or it won't work and you'll end up throwing out the baby with the bathwater. 100% honesty is as much about knowing yourself as it is about not misleading others. Only once you understand yourself and your motivations can you start to experiment with just saying stuff that's on your mind without thinking about it first. The things you say will clue you in on deeper motivations that you can then work on being honest with yourself about.