The longer the belt the more expensive it gets.
Belts do not like being bent backwards and the wider the belt the more damage back bending does
By using 2 belts, the actual shock loading on either belt is reduced .
IF set up properly , the blade only belt would be at a lower tension than the engine to deck belt so when the deck gets overwhelmed that belt will slip rather than break
Very common to run an engine to deck belt and a separate blade belt for the same reason.
For some reason Ferris decided to add the left blade to the PTO belt.
The blade that does the most work, is the right ( discharge ) blade and is the one that jambs most often.
