No. It takes a lot of power to close an app, it takes even more to open it up again. Doing this will reduce battery life, you’re better off leaving them open, iOS has very good RAM management You should only close an app in the quick-launch screen if it is “misbehaving” - not working right, or if it is using energy (as per Settings/Battery) and you don’t need it at the present time. There are several reasons you should not close apps.