Yeah, there are spots on the AT that might require 8 days or so. Generally you get an easy 5-6 days, sometimes shorter, between resupplies. This depends on your pace, of course.
I generally don't care about mail drops. I don't usually use them. I carry about a 10 pound base load for longer summer trips, so, my food is the biggest portion of my pack load. Sometimes as much as 25 pounds for two weeks out. (After I get settled in to a long distance trip, takes about three weeks or so, or, till everything consumable has been replaced at least once.)
I usually take some vitamin/mineral tablets. So, my only worry is really calories and protein. The occasional stop in a town usually will net an apple or two, or an orange, or some fruit along with a large sub, usually over stuffed with lettuce, tomatoes, pickles, peppers, olives, etc. I rarely eat junk food, but crushed Fritoes is always good to have around. Rice, spaghetti, peperoni, dried beef, jerky, cheese, etc, supply enough protein and fats for fat soluble vitamins. Cocoa, oatmeal, cream of wheat, nido or instant milk all supply medium/high density foods/medium/high density nutrition. Rice Sides, beef stews, soups, mashed potatoes, etc all supply plenty of calories and enough variety to not wear them out entirely on long distance hikes. Once per week, I spend a couple hours cooking. Breads, muffins, etc keep for a couple days. Cheeses are purchased by the pound. Often I carry two pounds of different varieties (Mozzerella chunks, minced garlic, a dash of red pepper rolled into dough and fried in olive oil is quite tasty, very dense, and keeps for two days.) A pound of hot dogs keeps well, too. A dozen eggs, boiled at camp, keeps for about three days. I pick the occasional dandelions, wild carrots, etc. They are nice in soups/stews. Later on I look for apples, but don't eat too many green ones. These are good cooked in oatmeal. Or, if I find enough, boiled up with some bullion.
I never use mail drops unless I need to change clothing/tents or the like. All my food is purchased as I go/as I find it/as needed. Nope, I never use dehydrated meals, either (unless you count Rice Sides.) However, many convenience shops only have "larger" boxes of stuff. Sometimes, this means just leaving the extras, often in the garbage. For example BisQuick. I buy a box but only use about 1/3 of it. That will last about a month on the trail.
