again the routing of the belt and the block height were the factors. If I remember correctly, over 40 years ago now, the horizontal there back and there again route was shallow and different forces tended to build on the different length runs and reset/relax on the long leg. this could overcome a spring loaded tensioner creating belt chatter and protentional damage so a fixed tensioning protocol was used when tensioning the belts. By this time belts really suffered little stretch so setting to a prescribed tension was not a risk factor. I'm sure there was a service tension check though between time or mileage belt changes. I'll look out my paper work and see if I can find that for you.
