I learned on a manual typewriter over fifty years ago but I use the pad on the right almost exclusively for numbers, probably because I used to use an old adding machine with that number keyboard and am used to it. I used to be very fast with the adding machine but I am much slower now on the computer.
I too use a ten key adding machine by touch and frequently throughout the day because of the type of work that I do. The way I do it works for me without slowing me down and I see no reason to change. Have enough other irrelevant stuff to learn just to be able to get to what is really relevant so I can complete a task.
At least someone had the wisdom to accommodate people like me by leaving the number keys on the top row where IMO is the only place they belong.