I think there's a lot of confusion here, between two or perhaps three totally different issues: soft images, AF optimisation, and AF microadjustment.
The AF setting guidebook is about optimising the setup of the AF system for "difficult" subjects. Right out of the box, on its default settings, it's already excellent. But if you know what kind of thing you're shooting, you can tweak it so that it can take advantage of that knowledge and perform even better. For example, if you're shooting a tennis match, you'll be focussed on the player's face, and you don't want the camera to lose focus if the racket momentarily swings through the AF zone. So you can decrease the tracking sensitivity of the AF system, so it will stay focussed on the face a bit longer without being distracted by the racket. Alternatively, suppose you're waiting for your subject to appear from behind an obstacle, and you want the camera to lock onto it as fast as possible. In this case you increase the tracking sensitivity. The default settings will do a good job in most circumstances - and probably about as good as any other camera on the market right now - but the AF settings can help it do a great job in specific circumstances.
AF microadjustment is something different. That's about tweaking the AF so that it works as well as possible with your specific lenses as opposed to somebody else's lenses. The tolerances to which equipment has to be made these days are incredibly demanding, and getting all equipment identical to within these very tight tolerances makes manufacturing expensive. The manufacturers have realised that it's actually more cost-effective to achieve a "reasonable" degree of consistency from one item to another, and give the user the means to tweak them to make them akll work perfecrtly together. So that's AF microadjustment. If your lens needs a large adjustment, that doesn't mean there's anything at all wrong with it. It's simply that the lens is at one point in the tolerance window and the camera is at a different point.
Now if your images are soft, therte are zillions of reasons what that could be. Not having the AF microadjustment set up correctly is one possible reason. Not having the AF optimised for your situation as per the guidebook is NOT likely to eb the reason thouigh, befcause that's all about getting a better hit rate on the "hardest" targets, and by definition most targets aren't the "hardest" ones.
Does that make sense?
@Jackwow?
