Students sometimes ask about taking spare socks with them outdoors, so if their boots and socks become wet they can change.
My answer is that if you have wet socks you will also have wet boots, so spare dry socks will simply become wet again.
If you are over-nighting then definitely bring spare socks. Nothing nicer than climbing into your shelter or sleeping bag with dry socks on your cold feet. However if just outdoors for a single day I would wear a pair of good quality hiking socks, with a thinner pair of socks over or under them.
Wearing two pairs of socks is super comfy, protects better from pounding and blisters. Also if your boots become wet two pairs of socks gives you a wetsuit type effect, hopefully keeping your feet warm.
By all means empty your boots of water and wring out your wet socks if need be. In tough conditions too much stop/starting and messing with boots/socks can become an issue. I have seen this slow down a group far too much, resulting in being caught in darkness and the inset of hypothermia. If your feet are wet simply keep going, unless you have a good reason for otherwise.
Best of all though keep feet as dry as possible for as long as possible. This means good quality leather hiking boots, with a good welt and a high rand. Laced securely. A pair of gaiters. Waterproof trousers on in advance of being needed. Walking pole in boggy ground. Good route choice and navigation planning, for example, instead of cutting through a depressed wet boggy area choose to follow a spur or ridge to the side.
Nathan - Outdoors Ireland