Actually, if you have used cashback cards before, it is not the same as % discounts at shops/outlets. They are only broad categories (divident and everycard), and for UOB/Stdchartered, its based on amt spent.
I already have as much as possible and am now making the decision to focus on ONE cashback card. I have enough cards to cover all banks for specific % discounts at particular outlets.
While there is no harm getting too many cards (if no fee).. If spend a little on each card.. then no point getting too many if the points can expire.. they probably expires before you ever get to redeem anything..
Back to the topic, OCBC Uplus Card. It earns linkpoints at various outlets, and the linkpoints can be converted into instant cash at Fairprice (so something like cash rebate essentially)