I agree with you that feet are 'funny things' which is why I have made a real effort to make my shoes and boots really personal to ME. I've found because I took the time to find out and how my feet work, or don't work, I can now walk more comfortably and longer without all of my previous gripes, sore balls of feet, aching ankles, one foot worse than the other, blisters, and so on. I now only experience one problem, around day two or three my toes start to 'lock up' and are painful with a 'burning' sensation but by day five or six the pain/ache just vanishes?
But as for shoes, boots, and trainers, I'm a bit opposite to you. I have one pair of summer off-road trainers, one pair of summer boots and one pair of everyday shoes, and one of each for the winter months. I don't change them for other shoes until they wear out. I don't wear trainers as a routine so I don't own a pair for walking street use.
I've tried a few types of socks but for me, they really don't seem to impact on my ability to hike, I mean I don't notice anything particular about socks other than some obviously feel different and some 'move' in my boots and some don't. I prefer the non-sliding ones. I just carry a couple of pairs and alternate them, including wearing them outside in and inside out.
For me these days the essence of having good hiking days is to treat my boots, socks, underwear, and trousers as one working unit, if they all working together in harmony then I feel good, if they don't I don't feel good. So for me, to try to get it 'right' I divide my body into three distinct parts, feet to waist, waist to neck and lastly my head.