We had a really bad experience at Kroger today and I won't go into all the details, but I did want to pass on what it boils down to.
While you can earn multiple $3 Catalina coupons in one transaction from the Daytona Mega sale, you can only redeem one of those coupons per transaction. So if you have say 5 coupons, you'll need to do 5 separate transactions in order to redeem them. Unless you plan for this from the beginning this could become a very big issue and you may find yourself unable to redeem them at all.
The Catalinas are only good for 2 weeks from the original purchase where they were created.
Some stores are over-riding this and allowing you to use multiple Catalinas in one transaction, however others are only allowing the one.
My suggestion is to plan for this from the beginning (if it's not too late) and do one single transaction of 10 Mega items at a time, earn the Catalina then do a second transaction to use it (and possibly earn a second one) and continue rolling them in this manner until you are done.
I'm now stuck with (9) $3 Catalinas and little likelihood of actually being able to use them all before they expire.