Yes. I shoot for 12% weight loss and measure initial weight before I put them in the incubator, then calculate final target weights for each egg in Excel. I figure out what amount of weight the egg should lose each day to obtain the target weight loss by day 18. Then I multiply the daily target weight loss by the number of days since I set them. So if I"m measuring weight on day 6, I take the initial egg weight and figure out what that egg should weigh on day six, and then compare to actual egg weight on day six. If the actual weight is higher than expected I might decrease humidity to increase weight loss. If weight is lower than expected, I might increase the humidity slightly, but this rarely happens in my setup. Then give it a few days to a week and measure again and compare to targets.
In order to get good hatching results, all the eggs you set should be as close as possible to the same size, and have the same shell permeability. You can only set your humidity at one value, which may not be optimal if you have a wide range of egg sizes and/or shell permeability. So large eggs and small eggs should be hatched separately (due to size and how much moisture has to evaporate for air cells to be the correct size at hatch), and Marans eggs and other eggs may need to be hatched separately due to differences in shell permeability.
