I started out over half a century ago with HO, then boxed it up and after about 2 decades made a layout on a tight 4.5x4' frame, packed it again as I moved, and now am resurrecting it all. Almost every piece was made from kits, both HO and some OO.
From my recent testing of the trackwork, all 100 guage, I find that many of my older and also newest rolling stock incl. engines have a habit of derailing, especially at frogs. The phenomenon is perfectly described in hon30critter 's critter video. The longer the truck the greater probability of derailment.