How I handle encumbrance in my OD&D/AD&D.
First, by Armor worn:
No armor - 12"/turn
Leather/Chain - 9"/turn
Plate - 6"/turn
If someone bears many weapons (more than four light, or two heavy weapons), or has a lot of gear, or carrying something obviously encumbering (like both hands on a chest full of gold), they move at next lower level.
The slowest move is 3"/turn.
I do allow adjustments for high strength - usually based on the "to hit" bonus.
Easy peasy.
My encumbrance rules are based on an evolution of how I look at D&D and how I want to play it. Eventually, I came back to Chainmail's POV and let armor dictate the lion's share of the move. Encumbrance is more than weight, it's about carrying/dealing with awkward loads and (potentially) restrictive armor.
I guess I should have made a blog post about this :P