This is also a downside as there are more belts used and therefore more room for belt-buffer and everything is less compact. This is a good measure to combat 'spaghetti factories' as it forces someone to plan a structured layout and move everything to use items from the bus. The concept of a Main Bus is to put the most used and useful ingredients in a central spot to use for assembling machines.
The main bus in use with several different items and some production