Still trying to get Shiny Litwick! I havent been counting my eggs and am Curious as to why people do? How do you guys hatch your eggs? Do you stack them in a bunch of boxes till you have so many than hatch? I personally just put them in my party with 1 pokemon and GO!
Also what does the Everstone do when your breeding?
Personally, when I MM (and this is just me), I empty my team except for a Volcarona with Fly (since Volcarona has Flame Body), put my Korean Ditto and my Pokemon that I want in the Day Care, and start collecting eggs. I keep the eggs until I fill my team, dump all but one in the boxes, collect more, and repeat until I fill a couple of boxes. Then I hatch them all and start over. This isn't the most efficient way to do this, because every time you get an egg, it finishes out the current cycle of your step count. Some people count their steps to get all 250 steps removed. I don't do this. Some people also collect eggs and just fill their boxes, and hatch them all at once. The most inefficient way to MM is to collect 5 eggs, hatch them, and start over.
People count eggs is just for the novelty of it, so friends can keep up with how lucky or unlucky we've all been lately. It's also fun to be proud of your hatching accomplishments and say, "It took me 9,000 eggs to get that Shiny Litwick...but I persevered and got it!" Or, if you think you have an English-hacked Ditto with Japanese characters (like vandslaux above you), you would know because each of your hunts is taking approximately 8,000 eggs, when a real Japanese Ditto would give you at least one or two hunts of 1,000 eggs or less.
If you put an Everstone on a FEMALE Pokemon (it can't be male), the offspring have a 50% chance of having the female's nature. This is especially useful when you want a shiny with a particular nature - it increases your chances of having the desired nature from 4% to 50%.