Sometimes a collection of recipes, mnemonics, acronyms, catch phrases, rules, or mantras of rote memory are useful to acquire and recall useful guides for action, sometimes however, understanding
a simple principle which can be applied to multiple contexts is far more useful and powerful (requiring less memorization but obligating you to a modicum of mental processing....)
Rather than memorizing any n-point perspective rules, simply remember: Parallel lines in reality, always appear to meet at the exact same vanishing point andNon-parallel lines in reality, never appear to meet at the exact same vanishing points.
This applies to any number of edges on any number of the same or different objects and any surroundings.
A corollary of the above is that any line parallel to the horizon vanishes at the horizon.
Have a great weekend!