Contrary to popular belief and in the face of an extremely common habit for many of us, it is advisable to leave your most frequently used applications open rather than systematically closing them. Restarting them over and over again will require much more energy and will therefore be harmful to your battery over time.
Whether you have an iPhone or an Android device, it isn’t necessary to close your mobile applications as soon as you stop using them. On iOS as well as on Android, it has actually now been demonstrated that constantly closing your mobile applications to reopen them later in the day is counterproductive and in fact uses more battery power than leaving them constantly open. Running in the background uses less energy than having to start up an application over and over again.