^ Your 4th paragraph, for me, has always been the biggest problem with the WM3. JB's own uncle doesn't corroborate his alibi on mowing the lawn that day. On top of that, DE and DT (who evidently went to watch their friend mow a lawn, which in and of itself is befuddling) say they had to walk to the laundromat that was literally a stone's throw away from JB's uncle's to get picked up by DE's parent; even though JB's uncle owned a working phone and that DE was always allowed in the uncle's home. There was absolutely zero reason why they would have had to walk to the laundromat to call and get picked up, but they said that's exactly what they did. Why? Most likely because they knew they had been spotted at the laundromat and had to incorporate it in their alibi in order to avoid suspicion. Remember, there were reports that LG had stated he "laundered" clothes.
It was also reported that JB, immediately after the crimes, traded weapons for cassette tapes -- these weapons were an ice axe and a curved sword w/sheath.
People like to poo-poo the JM confessions, but the truth of the matter is, he does get many things right. Yes, there are inaccuracies (which he explains were purposeful in order to throw off detectives, which makes sense in and of itself, but I digress), but he was right about which particular victim received which particular injuries, particular injuries that were never reported (such as the ear-pulling), and his route home from the crime scene, among other things I can't think of off the top of my head.
That said, and what makes this case so difficult, is that: could this have really been the murder site? Could this have been enacted by 3 teenagers, who were able to leave practically zero evidence, shoe prints, foot prints, and minimal amounts of blood at the scene?