It's not just checking, its download also, it make update take more time and keep making unuseful download
The download is not "unuseful" ( "useless" might be a better word ), there's a reason for always downloading: it's because we don't try to reinvent the wheel, so we leave the task to CHECKING if an update is required, to the Microsoft installers themselves, which will surely know better so, clearly, we must first download them in order to start them, so they can do their own thing, which is CHECKING+UPDATING(IF REQUIRED)