Even though I can see how poles can save your knees, I rarely use poles in the summer, usually only if I’ve a heavy load, which isn’t often these days in the summer! Prolonged use on hard surfaces I find just causes elbow and sholder pain – you just transfer the pain from your knees to other joints!
Walking poles in summer(!)
Winter however, I’m more inclined to use them – heavier loads, deep snow, the need for balance being offset and softer surfaces absorbing impact. People do over use poles in winter – how often do we see walkers and climbers on steep ground with their poles out and ice axes strapped to their rucksacks? Well, that’s a disucssion for another day!