When you started making knives, the entire process was foreign and new. You learned to get better at forging, grinding, finishing, fitting, woodworking, shaping and all by jumping right in and applying the book knowledge you gained by reading or watching videos.
When you made your first knife, regardless of how pretty it turned out, you learned something. Usually something you can apply to make the next knife better, but often you'll find out a trick that made some part of the process easier or better somehow.
Now because this was your first knife, it was new. Because it was new, you learned something. This principle carries on whether you've made five knives or five hundred.
So what I like to do is every once in a while, is build what I call a "Novel Project".
The Novel Project is something new or unfamiliar to me. It could be a Katana, it could be a chefs knife, it could be a folding knife.
By now I have the basic know-how and experience to have a good idea of what to do in each step, but having not done it before forces me out of my comfort zone and to find new methods to get around unique challenges, especially those that are unique to me and to the tools available.
The best thing about a Novel Project, is if I return to try making it again at a future date, the second time around is far better than the first. This is both because of the experience and knowledge gained the first time around, as well as my natural improvement from other projects over time. I only fully realized this when I went looking at pictures of some of my old work. These are all the daggers I've made, four in all, with roughly a year in between each.
The photo sequence is a little wonky, but it's quite clear in which order they were made. Bottom left, top left, top right, and finally bottom right
Now I talk about using a Novel Project to get better, to stretch your skill muscles and to gain experience. And that's all true, but to be really honest, my motivating factor for them is to have fun. That's really all it is. Usually a Novel Project is spurred on by sudden inspiration, and it's really a revival of my first love for the art. Everything else is a bonus, as great a bonus as they are.
Of course it's good to stick with one style for an amount of time; my preferred one was small bowies, but this is about the benefits of doing a Novel Project.
Now to continue my earlier point: the first novel project in a certain type (say a chef knife) dips my toes in the water, and often is a complete failure. The second one usually is fairly passable, but not sellable. The third, I can refine the points and mistakes I made last time. The fourth, I can focus on the details and trying to excel. At this point, the novel project has become familiar, and if I like it I'll continue doing it, but it's no longer a novel project. About this time I'll get the bug to try something different, say a katana.
Over time this all adds up. Every time you do something it becomes a little more familiar, and you gain a little more skill. It's very much like a video game; as you get better at the game and play it more often, you unlock new characters, and harder and harder levels. So it is with knife making. As you make knives, if the attempt fails, you've learned enough to correct it next time, and as you get better, you gain the skills to attempt new novel projects that would have been impossible a dozen knives ago.
This, coupled with the attempt to make each knife better than the last, is the real way to improvement. After all though, it's all about fun. We put far more effort into the job when we enjoy it.