What are rules about cooking lamb and chicken doner kebab? How many times can the spit be put in the fridge, then cooked again the next day? I have been to a kebab shop where the cook put a huge lamb vertical doner spit in front of the grill, totally frozen. He told me it would take about 20 mins till ready. I asked how many times he puts it back in the fridge. He replied, "Until it's all gone." 
ONCE ONLY I am sure rules will vary depending on country etc and which jurisdiction and laws apply. In England my country reheating a kebab would not be recommended *, although even as a customer it is possible to visit shops at opening time and observe that a part used Kebab has been loaded. Reheating it a second time is forbidden *. Local Councils (District Councils etc.[D.C.]) enforce food safety, in accordance with National Regulations. Taking some random councils and their advice  Hambleton D.C. Good Practice   Keeping part used kebabs or leftover sliced meat is not recommended. It is safer to use fresh doner kebabs each day, and minimise waste by selecting smaller sized blocks of meat that suit the demands of your business. ... When re-heating part used doner kebabs make sure the vertical spit is on full heat and the cooked meat is above +75 ̊C   Brighton & Hove City Council Prepare and cook doner kebabs safely   throw away any meat you’ve sliced or left on the doner kebab when you close, do not cook or reheat it keep your doner kebabs as small as possible to avoid food waste   Ahfield D.C. Safe Preparation and cooking of Kebabs   Partly cooked meat which is left on the kebab must be thrown away as it [sic]food poisoning bacteria may be present Raw meat on the spit must be cooled quickly within 1½ hours and put in the refrigerator away from other foods - stored in the bottom of the fridge so raw juices cannot drip onto cooked and ready to eat foods   * reheating a kebab would not be recommended You can see Council advice may differ slightly. There are set rules on times and temperature and regulations saying these must be logged. In addition there is Health and Safety legislation requiring Risk Assessments. It appears some councils decide the safest method is to throw it all away at end of Service. Whereas others seem to accept all protocols will be rigorously followed, and there will be no cross contamination between batches of meats so uncooked meat may be frozen or chilled until the next day. * Reheating it a second time is forbidden No wiggle room on that one. Anyone with just the most basic hygiene training knows we are only allowed to reheat once. [National] F.S.A https://www.food.gov.uk/business-guidance/cooking-safely-in-your-business?  Reheating food It is very important to reheat food properly to kill harmful bacteria that may have grown since the food was cooked. Reheating means cooking again, not just warming up. Always reheat food until it is steaming hot all the way through. You can only reheat your food once.  