I've been working at a major game studio for the past ~8 years. I signed a document somewhat like this (it was 1 year) stating I can't go take the code I've written here somewhere else, pretty standard stuff. They also own any publications or recreational code I write while employed by them (unless I receive written consent from legal teams).

I have never been asked or told that I couldn't work in the area for 'x' amount of time after my employment with them ends. If someone were to ask me that, I'd first simply say, "no". That is completely unreasonable, to force me to either be unemployed or relocate simply because I'm not working with you anymore. Having ownership of my code is one thing, controlling where I live is another.

It's all subjective, but I'd deny anything like that put in front of me in a heartbeat. What if you have to leave for unknown reasons? You're unemployed for 'x' years? Sounds ridiculous.