I'm using F12 and have found that even as little as 5 min/entire game uncovers lots of stuff both me and my occasionally hapless opponents totally missed or didn't consider important.
Analyze the same game over and over again with different TLs for starters to see if that makes any difference, or with the same TL and different threshold etc.
You can also load lots of free engines into Fritz inc Firebird, Houdini, Stockfish and Critter and compare their results as well.
Looks like you've got a lot of work ahead!
just wondering what parameter settings people on here use for fritz for analysis, i.e 10 seconds with a threshold of 300 etc ???