How sync works
After you’ve set up your device to sync, Windows automatically syncs files with the device any time you connect it to your computer. If you leave the device connected for a long time, Windows checks for new contacts, calendars, and similar types of files to sync approximately every 30 minutes. Windows also checks for new music, pictures, and videos that you have set up to sync, but only when you connect the device or click Sync Now in Device Stage.
If your device is set up to sync automatically, this can drain the battery quicker than if sync is turned off. If it seems like Windows is taking a long time to sync some files, it might be due to the types of files it’s syncing. For example, video files can be quite large and take much longer to sync than music or photos.
If you’re about to sync many files—such as your entire music collection—with a new device, it might take a long time. After you’ve finished syncing the files once, however, Windows will only sync new files next time, which should be a lot quicker.
Device Stage allows you to sync as many folders on your computer as you want with a device. However, you can only sync up to 50 folders that aren’t in your Windows libraries, such as your Music Library or Photo Library. If you have more than 50 folders you want to sync a device with, make sure they are in your libraries. For more information, see Working with libraries.