A yield bonus of x1.2 does not actually alter the YIELD, it alters the NUMBER OF CRAFTS, rounded down.
For example, if a single craft normally Yields 3 units and you queue 2 crafts, the Yield is 3 x2 or 6.
If you had a yield bonus of x1.2, the final yield is (3 x rounddown(2 crafts x 1.2 bonus)) or 3 x 2 = 6.
If the Yield bonus of x1.2 actually affected the Yield, you would have rounddown(3 x 2 x 1.2) or 7.
If you have yield bonus of x1.2, you would need to queue 5 crafts to get any bonus: (3 yield x (5 crafts x 1.2 bonus)) = 18.
Also, i noticed on my refined saw table that if i put a tier 1 augment (1.2x) and a tier 2 augment (1.4x), the final yield will get the tier 1 bonus instead of the tier 2. That doesn't happen with other crafting tables