What you should know, I believe Satoshi placed the keys at least in 50% + of each range, which makes solving them counterproductive financially.
Faith will move mountains, but knowledge will move them faster. The keys position within its range are randomly. You can proof yourself, just check the keys and calculate its position. That's no rocket science. Hint: look at puzzle 25, 31, 60, 63 to get a feeling of what a high position is and puzzles 38, 50, 85 to understand what a low position means

There is no "narrowing the search range solution" for this. You wouldn't have solve the mentioned puzzle otherwise. The key positions for the known keys of today for this puzzle vary from 0.069 (puzzle 38) to 0.97 (puzzle 60), while disregarding puzzles 1-10.
Believe nothing, no matter where you read it, or who said it, no matter if I have said it, unless it agrees with your own reason and your own common sense.
The creator said - these are deterministic addresses with keys that are truncated to the right bits! I think it's true! The keys have no dependency and no logic! Not only were they randomly generated, they were also cut off after that!!! No need to look for a black cat in a dark room - especially if it's not a cat there!!)) Without hints to the main key - only bruteforce!!! It's very sad!