(note; there can be a 5th W ...a DOG
in the last minute of a 50-0 game = WHY? 
I had a game this year that was a huge blowout like this. Running clock, and the losing team was dragging their feet getting plays in an called. At one point, the visible play clock (which they would not turn off despite requests) was running to zero with the team still in the huddle.
Wouldn't you know it, but, I suddenly had to verify that we had the right down. Crazy coincidence... only piece of luck that team had the whole game.
There can be a big difference between “a foul during a loose ball play” and “a foul while the ball is loose”. It’s really hard to explain this difference to new officials.
I’ve always thought that the term “loose ball play” should be changed to avoid such confusion — perhaps to “non-running play”. Anyone have any other suggestions?
I figure this is a weird holdover from the rugby roots, especially league, where you have six tackles and phases, but it's a continuous action - so a "play" is part of the live ball action, and there can be many plays before the ball becomes dead.
In the rule book, I figure this is also one of those things that has become unnecessarily complicated due to a bunch of minor changes over the years. However, with the recent change to Rule 10 (the part they meant to put in), I think it can simplify it a little bit:
Prior to any change of possession, if a foul happens while the ball is loose (or prior to the ball being loose on a legal forward pass, legal kick or fumble) the basic spot is the previous spot of player possession (i.e., where player possession ended) - except that spot cannot be behind the line of scrimmage. (Sub-exception for spot fouls listed in 10-4-4).