Spark plugs. Why is it so hard?

SparkPlugs.com: Champion Spark Plug Numbering System
As with most questions on theses sites the members tend to bombard you with 100 times more info than can be absorbed.
A guy thing I guess.
In stock applications, Safe bet is to stay with what the factory installed. Once you start to change things, now you must rely on your own research or take a chance on someone else's opinion of which there are a million. As with anything else there are 2 ways to get answers to questions.
Look it up, research the subject so you have an understanding of how to get the answer and what it means. This makes you a future resource.
Or just listen to someone else, throw a dart and hope it works and then when it doesn't do what you expected, have no idea why.