I made a test where i refined 10000 mats in ten batches, 1000 mats each and recorded the result:
Thousand mats is so low amount that the golden drop rate keeps jumping up and down between batches. In fact the total 10000 mats gave unusually low rate. Sometimes even ten thousand mats isn’t enough for reliable results!
Now, compare this to those forum posts where people refine few hundred mats and declare that drop rates have fallen. Tsk tsk.