Doing a runner after you've signed a contract and within 30 days of your entry date into China with your Z visa will certainly work provided you've not been issued with an RP!
And it's exactly the treatment mean and sneaky Chinese employers deserve. They try to save themselves the cost of the RP just in case the FT they enticed from abroad is a crap teacher, and has to be driven away! In that case, he'll be fired and only have the rest of the validity of his 30 day Z visa to spend in China, as it will 'revert' to an L visa, plus a 10 day L renewal,if he decides to pay for a new visa to extend his stay in the country after being fired. Some Chinese employers need 25 days to decide whether or not to apply for an RP on behalf of their FT's. Those who are deemed lousy teachers by their Chinese employers can simply be let go, even after 27 days or so of TEACHING ILLEGALLY, ie without an RP! Then they've just 3 days left to exit the country without having overstayed. BTW, the fine for each day of overstay is 500 RMB/day,up to a maximum of 5000RMB.
But if the employer took the FT's passport off him as soon as the foreigner arrived at the school in order to get the RP for said louwai processed ASAP, then the new FT couldn't run. How stupid, distrusting, cunning and shortsighted Chinese employers can be. It serves them right that they have been duped by louwai who have realised they can't hack the job nor the place after a few days, and run, run, run, at the weekend..LOL!
Oh! Weekends are marvellous - thank God for them. Runners can run while Chinese employers eat and be merry. But then there's the Monday blues for the Chinese employers, no FT! Never mind, don't care about the foxy Chinese employers! Instead let's have a good laugh at them! They've been outfoxed!