If the company says "sign in the next 5 minutes or else" than maybe. But the company wants you to sign.
And the lawyers who crafted up the contract don't want it to be thrown out for some stupid reason, so they will advise your (about to be ex-)employer to let you take it home to read it and think about it.
And the lawyers who crafted up the contract don't want it to be thrown out for some stupid reason, so they will advise your (about to be ex-)employer to let you take it home to read it and think about it.