Something I haven't seen mentioned here is changing flying fields.
My brother and I flew a lot with the local club during their free training nights, it's great to see people spending every Wednesday of their summer helping people with their planes, and we have both somewhat soloed a time or two. Well we felt like we could take them out to a large salt flat area which is pretty much unlimited runway and fly on our own. Well that was a wrong choice we both wrecked but we both think it was because without enough solo time we weren't experienced enough to compensate for the change of landmarks. We both were lower than we thought and I wasn't as far out as I thought. So I think familiar surroundings are very important until you have a lot of experience.