Colemak
I've always wanted to type correctly. By that I mean touch-typing using 10 fingers and with finger on the right position. I got the touch-typing part nailed pretty good. The 10 fingers? Sort of. I'm pretty sure I'm using all my 10 fingers to type. Do I use it correctly? Now that's the concern. I don't think I do. And it's hard to change the habbit.
I figured, if I wanted to change the habbit, I might as well learn new layout. Partly because I felt the muscle memory is easier to change if I learn new layout, partly because I just wanted it for the sake of it. I picked Colemak, because most of the GUI shortcuts (like ctrl+c, ctrl+v, you know, 2 most important shortcuts for progammer) stays on the same position (as in qwerty). So I changed my layout in OS level and started the journey. I put this image on my second monitor as cheatsheet. I also printed the image and put it next to my keyboard.
I made a note about it on the first day, second day, and after a week. My firt day was on May 22, 2017.
Day 1 was painful. My typing speed was probably 3-4 WPM. My second monitor was practically used to display the keyboard layout. Also, I had to switch between QWERTY and Colemak otherwise I won't be able to work at all.
Day 2 was probably the same. My brain could figure out the key position, but my muscle couldn't. Could've been much better if I didn't switch back and forth. Alas, work needed to happen.
Day 8. 22 WPM. That's an improvement. I realized something. A lot
of shell commands I do come from muscle memory instead of
remembering the command. So I kept hitting cd at the
qwerty position. Also, I've been typing cd using the wrong finger the whole
time.
After that, the improvement is gradual. I think stopped switching back to qwerty after day 8. I was never a fast typer, so I don't really care about my WPM. Now, after more than 6 months, I feel I'm using my fingers correctly. Having an ortholinear split keyboard helps too, but that's another story for another time.
So, answering the question you have, if you're using qwerty layout, should you learn new layout? The answer, IMO, is always no if you don't have any problem with it. If you have pain from moving you fingers, or you just want new challenge, go for it. It's fun.