water temp is most important for perfect eggs & don't over crowd. Vinegar or pickles are or lemons are useful to alot of people. They make the water easier to be kept clean, they change the buoyancy this floats the scum & blow off making it easy to discard with a sloted spoon. they also keep the eggs from cooking directly to the bottom of the pan. I've never cooked more than 20 at once but I have cooked 20 at once for several hours.I like to use a 2" hotel pan with a lid on it & just set it right on a 350-375 degree grill. Kept filled with water & I just use oil, occasionaly a lemon wedgethe procedure would go like this: remove lid from pan crack eggs into the water delicately & replace lid. The less you disturb the water the nicer the eggs. Poach just until the whites are solid remove lid & take the eggs out. I use a slotted spatula. Perfect every time. Discard & replace pan & water often. You will have to get your own feel for how long it takes before the eggs are done. If using a pan on the stove at home use about 3" of water use a lid heat the water to just about smiling, that's when you can see creases starting to form on the surface, when you see this back the heat down to med, add oil or cooking spray & add to that a slice of lemon if you want to, gently crack eggs into the pan avoid splashing the water around in the pan. put lid on, you will be able to get a slotted spoon under the egg to inspect for doneness in 2 minutes. Alternatively: fill soup bowl with 2" water, heat in microwave for 1:30 secs, crack 2 eggs into bowl of water & cook for additional 30 seconds remove & serve. Be warned eggs can blow up as long as 1 minute after taking them out.