Apple's earlier documents stated that when users use iOS devices during normal time, it is not recommended to completely close all background apps. Only when the app is not responding, it should be closed forcibly. But why can't you turn off unused software at normal times? Now I will answer the above incident to Apple's Genius staff.
Apple ’s Genius staff said that Apple ’s iOS system has dedicated resource allocation and power saving functions. When necessary, the system will allocate some of the software that was used a long time ago to the resources you are dealing with. At work, some software that has been idle for a period of time will go to sleep to reduce power consumption. The entire process is automatic, and there is no need to close the software.
And if the user is accustomed to closing the software after using it every time, then the next time you need to use the software, the system will reload the software, which means it will take longer to use the function you want. Reloading is more power consuming, so it is recommended to keep it in the background for commonly used software.