Relying on engine braking is what kept gearbox reconditioners in business in the early years of motoring. I copied my mates, changing down, then slowing to the scream of well worn gears and shafts on the over run. Then the penny dropped....It's quicker, cheaper and simpler to change a set of pads than change a gearbox. But we all did it, must have wrecked quite a few boxes.
Anyone who had a 1960's Mini will know the score. I'd say get those brakes fixed and don't use over run in lower gears. Also I'm more well behaved now.
Swarfy.