Yes, you are right. Battery draining issue solved, the device also gets super fats.
I'm asking this because I seriously don't know the use of factory reset so!
There are several reasons why a factory reset of your smartphone might be needed. If your phone is unresponsive for a few seconds when you go to the home screen, this problem shouldn’t be ignored. If you are noticing that there is frequent freezing of the phone when you are scrolling through pages or using apps, then resetting the phone can help to solve this problem. A phone that force closes too often can also benefit from a factory reset. Android is a multi-tasking environment, and various apps using a malfunctioning system can result in failure, which shows up as forced closes. Resetting the handset will re-establish a working environment and reduce the occurrence of forced closes, freezing, and other issues.
Yes, factory reset removes all data from your phone but you can take it back up before formate your device. You can use the Samsung Smart Switch app to take backup.