My experience says during the depression. When you don't change, other people change around you, which ultimately changes you. And that change in other people would remain longest time. They won't be the same as the time you spent with them. Same with finance, you have to change and shuffle the stuff regularly. And then in the workplace too. Some people change workplace every 3-4 years otherwise they end up being treated like peon in the office. Change is the constant.