Depends on how much disk space you have. The "industry standard" is to maintain the most recent three backup images (commonly called the three generations or grandfather, father, son pattern. This is because very often when you discover a problem (say a bad virus infection or bad update) and need to go back to an earlier image you discover that the problem already existed in that image and you need to go further back to an earlier one.
Well, honestly, if you are using backups created by Microsoft's built-in backup program in Win7--they are all completely worthless! I would find an Image backup program that actually works, such as EASEus Todo mentioned by northangrywolf in post above. Also, Macrium and Acronis we've tested thoroughly from XP-W10.
Relying on those Windows created-backups will only cause you grief and data loss.
Sorry to be the bearer of bad news.
<<<<BIGBEARJEDI>>>>
Well, honestly, if you are using backups created by Microsoft's built-in backup program in Win7--they are all completely worthless! I would find an Image backup program that actually works, such as EASEus Todo mentioned by northangrywolf in post above. Also, Macrium and Acronis we've tested thoroughly from XP-W10.
Relying on those Windows created-backups will only cause you grief and data loss.
Sorry to be the bearer of bad news.
<<<<BIGBEARJEDI>>>>