These should fix half of the belt problems:
Exit socket (every socket that is connected to belt and w/o selected input) should has same logic as machine input.
From belt pathfinder perspective, machine outputs and belts should be same.
Output from machines with higher production time should has priority over machines with lower production time (or belts, which has production time of 1).
Ideas for solving confused or stuck belt loops:
- Allow players to change direction of belt between junctions (ctrl-click, shift-click or something). Direction could be saved so it is same after save/load.
- Just move stuck belt in default direction, 50% of the time it will be right direction. If not, players can change it. (see point 1).