Previous employer tried to issue me a contract that was not just restricted to software. Any copyrightable work had to be offered to the company for first refusal. The contract looked like a cut/paste/edit job from a generic HR book.
As a serious amateur photographer I could take a few hundred pictures a week. Every single one of which is immediately copyrightable, even if just a holiday snap. I pointed this out to HR and the contract was amended (before signing).
The process for submitting your off-time works to the legal team was not geared up for bulk submissions and would have taken up my entire working week, every week.