Yeah watch out for Hobby Lobby. You agree to work there they try to get you to forfeit certain legal rights in exchange for the dubious "privilege" of working three.
Misconception.
You can't agree to forfeit legal rights in an employment contract. No matter what a company says, no matter what you sign, any portion of a contract that is contrary to public policy (i.e., the law) is unenforceable.
It's like the signs on the back of rock hauler trucks here in Las Vegas where they claim that you must stay back 200 feet because they aren't responsible for broken windshields. Bullshit. Of course they're responsible if debris is falling off of their vehicle. The same goes for car washes or dry cleaners. You don't get to absolve yourself from liabilty because you put up a sign and you don't get absolve yourself from complying with public policy because your employee agreed to it.
It's not uncommon for employers to attempt this for this the same reason that that hauling companies put these signs on their vehicles. They assume that the person reading the sign or signing the contract is stupid enough to think that it carries any weight and they know that most people won't follow up to take advantage of their rights.