You can prolong the 5% by walking inside the gas station, and if they offer their brand gas gift cards, buy them. It has been confirmed by Chase that you will get the 5% extra when purchasing a gift card inside the store.
You also get extra savings when using your gift card at the pumps or inside as they count as non-credit card transactions so you'd get the cash price on the gas per gallon.
I usually buy a good size $ gas gift card when the quarter is about over so I can continue to reap the rewards after the expiration of the extra bonus.
Just a reminder of what has always worked for me.
What I did to confirm is after purchasing my gift card, I'd call Chase customer service and they can confirm your % cash back with that particular transaction. There's never been an issue when it wasn't 5%.
Also if you have a BI-LO near you and use BI-LO Perks, this helps to use along with your BI-LO gas perks at the pump.