As @
TheCupcakeisaLie said, to prevent recipe clutter of each micro block.
And the recipe is simple and there are only 2 options for the saw: it's either on top or on the left side from the block
Example:
Put saw above a block (always start with this one) and you end up with half-slabs (from here options almost limited) Then you saw the half-slabs from the top to get Panels. Saw the panels from the top to get covers.
If you saw half-slabs from the left to right you start getting beams and each iteration ends up with a smaller micro block.
If you want nooks (or how it's called) it's a combination op ups and left(ie)s
Play with it, make a stone saw before you waste a diamond one on experimenting.