You will probably have a higher chance of developing technical skills if you take some time to study and code during your free time. You shouldn't depend on your job to train you on new languages or frameworks. There are a lot of things you and I don't know and we won't have time to learn about them while at work.

Also being a developer isn't just purely coding. There's the ability to write legible code, write tests, know what to use when, know how to read code that you didn't write (or even in a language you aren't a master of), find the cause of a bug in an efficient way. You need to be able to talk effectively to non-technical people to figure out why they think X is a bug or how Y is really supposed to work. Those type of skills kinda evolve during your work hours but you have to be aware about improving on them.

I think if you don't spend some extra time programming you very well might grow stale. Years will pass by and you'll realize you want to get a new job but you don't really know that much beyond what you did at work.