First of all, it depends on the QUALITY of your hay. If it was put up real late, it could be poor quality. If put up on time, may be perfect. What I do, is put out hay like your doing. When the hay runs out, I try to let them "scroung" for about 1/2 a day cleaning up wasted hay. Than I feed them again. Now, this is on mature cows in good condition.
Second, you need to know the condition of your cows. If they are thin, they need more, if in good condition, you can do like I explained.
But, heifers & cows nursing cows, should not run out of feed.
It's all in the "eye of the beholder". Also, check manure. If its real thick - firm, the protein is probably low. The softer (looser) the manure - the higher the protein.
Also, just because 2 bales last 2 days this week, next week the weather may change & they will require more. You have to adjust with their needs. Of course, I have the luxury of taking care of our cows full time. I can adjust my time schedule to fit theirs. Not true in most cases.
The reason I let the mature cows run out, is simple economics - I save hay & money. I'm cheap! Just my thoughts.