Thanks for the information. While it's better than no backup, another problem is "Previous Version" use low percentage of partition space. If the partition space is really small and user frequently write files, it's possible Electrum wallet files won't be or less frequently backed up.
Based on my research according to Microsoft the space size that they can handle for the restore point is around 3% to 5% of disk space depending on the hard disk total size.
Since the wallet file is not eating so much data space it should still have a restore point unless if the hard disk drive is totally full.