All a matter of preference. I use only one because I like having a free hand and being able to switch. I don't hit the trail without it, even day hikes. Defintely helps with stream crossings, rough and/or steep terrain. Spend as much or as little as you like, just don't let anyone tell you that you need to spend a lot to get a decent pole(s). Keep in mind it's basically nothing more than a fancy artificial stick.