I disagree with matt and macmac. I know that both do okay, and work fairly hard, but they are wrong about this.
Your round is governed by what is sustainable for you. That is why some guys can only earn a certain figure even after many years, and others smash every ball into deep cover.
This is not a lifestyle choice or a hobby. You do this to earn money and it's a numbers game ftp. Don't lose sight of that just because you gab for twenty minutes, or a customer turns you away, your system breaks, or you have a complaint.
Forget the niggles. You have reached a plateau, albeit quite a comfy financial one, but you need to push for the next stage otherwise you may be stuck there for a while. Don't look back and think, i could have made a go of that, but i opted just to earn a living and have an easy life. The so called easy life could mean you working on the tools for the next twenty years, and i don't see anything chilled out about that.