Absolutely, I find the 12k to be a great polishing stone. Nothing wrong with that at all.

Some people say the Coticule gives a smoother edge and that the 12k is sharper but not necessarily a smoothe edge. While still others claim the sharpness is what is good about the stone and that it is an improvement over the Coticule.

So, in essence, if it's working for you, than keep doing it. Maybe someday you'll feel like experimenting with other stones, but there is no necessity to do so. The 12k will do well for you, for a long time.

And congrats on being able to maintain your own edges! Not everyone has such an easy time at first.