My "contracts" were always in writing. Very clear what was being bought. Start of work date was also specified. Completion date was always iffy due to hidden problems and change orders, but once started, it was done till completion.. No "nail a board up and be back in a month"
I do not understand "contractors" who do not have written contracts.
I learned the hard way about contracts. I was taught that if you look a man in his eyes and shake his hand, that is more binding than any contract that an attorney could write for you. Unfortunately, not everyone was raised that way. I now have a contract, as you said, that is signed.