Do non-cloud Steam save files have a regular structure?

By "structure" I mean headers and footers that all (or a significant subset of) Steam games' local save files begin and end with. A .dat file extension or folder heirarchy is not enough, as I will be "carving" the data in binary form from a hard drive with a corrupted file index.

The platform these games were played on is Windows 8.1 Professional 64bit, with AMD processor and graphics.

Background info: I am researching data recovery options for a client with a failed hard drive who wishes to recover save game files from that hard drive, which are not backed up to the Steam Cloud or other media.

I do not need help with the data recovery process itself (which would be off topic here anyway), but only with identifying what, if any, predictable structure delimits a "Steam game save".

Though the ideal answer will cover all Steam-purchased games which do not sync to the Steam Cloud or were last played offline, my client is specifically concerned about saves from:

• Don't Starve
• Castle Crashers
• Battleblock Theater
• Super Meat Boy
• Bioshock 1
• Five Nights at Freddy's 1

I have explained that even with a well-known file format, forensic data recovery is likely to produce corrupt files due to damaged media, and therefore recovered saves may not be playable. However, if there is some (DRM) reason the saves cannot be loaded under the same Steam account, on the same legally purchased games, on a new laptop, I will consider it an answer as well.