I see so many places that could have roundabouts instead of lights. Plus, if the maximum speed inside my town was lowered to 40km/h, we could have shorter yellows. You can never reach the 60km/h limit for more than a few seconds anyway.
Speaking for Johannesburg, we can't have shorter yellows because too many people treat them is "last chance to speed up to make it through before it's red for too long!" and JMPD is beyond useless at law enforcement.