Whilst creating a furnace array I noticed that a certain furnace would not take items from my hopper distribution line. This furnace was in the centre of a chunk (Roughly speaking - Ruling out chunk boundaries as an issue) and there was nothing wrong with the hopper or the Redstone after checking. 

No matter where I build such an arrangement (Orientation or position), there always seems to be one or two furnaces that will not take items from the hoppers. Instead, the hopper seems to 'tick' earlier and push the item along to the next hopper meaning the next hopper will have an additional piece of fuel. This shouldn't happen as all hoppers are blocked by the same length on continuous redstone dust and so should lock within the same game tick, hence no discrepancy should occur between them.

I've added some screenshots indicating such an arrangement.