Some great points in this thread. For me it depends on what the foot care issue is. Tought to get around more serious issues like planters fasciitis.
I use layering to prevent blisters and my method has worked 100% regardless of distance, weight, boot etc... It starts with knee high panty hose. Laugh now, if you try it, you'll likely not stop. You can get a box of 8-10 pair at any Wal-Mart/Drug store for under $5. The next layer is a moisture wicking poly pro type sock. Current ones are by Wigwam and also assist with scent control. The outer layer is a merino wool sock thickness dependent on climate. Current pair are mid-weight Lorpen.
Last Dec packing in to AZ, was the forth day before I needed some moleskin maintenance and that was a previously healed blister spot due to another activity where I failed to follow my own method.
Like mentioned already, when I broke for lunch, I aired my feet out. All three would dry very rapidly and little to no scent. Combine this with Dead Down Wind powder and you've got a combination that will work in nearly all conditions.
Depending on how hard I push, my legs normally give before my feet. Need to remember to continually stretch, monitor water intake, and have some vitamin M on hand to address the soreness.