No. If you follow the letter of the contract, most IP assignments claim everything their employees do, but practically, that's just because it's impossible to write a contract that says "everything you do for your job, nothing that you don't".
The primary driver is that you don't want to get into litigating how much time your salaried employees work. So most employers will tacitly ignore side projects, only coming after devs who write code that steals users or shifts revenue from their customers to a project that a dev claims to own. And that's pretty rare.
No, as I mentioned, I'm a freelancer. Intellectual property for any project is strictly defined in the contract for that project. I'm also operating on my own equipment, as a separate entity, on my own property. Not to mention that clients are actually not allowed to get to specific with when or how I do my work exactly, without breaking some Canadian (and I suspect American), rules related to distinguishing contractors from employees.
Could you elaborate on defining the intellectual property in your contracts? I've had questions about how to do this correctly recently while negotiating one of my first independent contractor agreements.
The primary driver is that you don't want to get into litigating how much time your salaried employees work. So most employers will tacitly ignore side projects, only coming after devs who write code that steals users or shifts revenue from their customers to a project that a dev claims to own. And that's pretty rare.