If you’re referring to total ownership, it’s absolutely been tried. It’s boilerplate in some standard contracts. I crossed it out of the contract when onboardin

If you’re referring to total ownership, it’s absolutely been tried. It’s boilerplate in some standard contracts. I crossed it out of the contract when onboarding at my current employer (thankfully, they didn’t object at all to rewriting it to cover only work done during work hours or using company resources, which is perfectly reasonable). I think the idea behind total ownership is that if, say, you’re a chemist researching temporary adhesives based on petroleum, and you’re in the shower one day when your team’s petroleum research suddenly inspires an idea about a temporary adhesive based on latex, they don’t want you going out and either selling that idea to a competitor or starting your own company. And they might have a case. In general, side projects closely related to your employer’s line of business are a recipe for trouble anyway, and I don’t recommend it even if your contract is permissive about IP.