>>1156023Hiked around the Alps for 5 days back in September, nothing too extreme (no glaciers, just hut to hut, on average 10km air distance, +800 and -800 altitude difference per day), and though I usually don't sweat a lot plus it was rather cold and snowy, the boots were quite wet inside by around the 3rd day (25cm tall and waterproof so it must've come from the inside).
Didn't help that none but the first hut we stayed in overnights didn't have proper drying rooms, so you had to leave the boots in an unheated front room at around +5°C, so nothing could dry out.
Double socks (inside thin cotton, outside thicker, taller wool ones) helped a bit and I got away without any blister.
But if I were to do a similar trip again, maybe even longer, I'd seriously think about bringing along a second pair. My backpack had 14kg anyway, so I guess an extra 2.5kg would be worth it to me as long as the feet you have to rely on all day stay safe and comfortable, but it's something you have to weigh down for yourself (less strain on back vs feet, I personally prefer the latter, because at 1.90m/80kg I can "afford" it)