I did what you are doing for 3 years or so in the beginning. Nothing particularly wrong with it. The only reason I'd switch to using Version Control if I were

I did what you are doing for 3 years or so in the beginning. Nothing particularly wrong with it. The only reason I'd switch to using Version Control if I were you is that managing the file copies and different directories with features you are working on can be a hassle. You tend to have extraneous files lying around. Plus with VC you get nice histories on all the files.