About few months ,the reason I'am doing that amount is the nearest OD stores are about 60 miles away ,so I visit them on a weekend and buy about 2-3 k per card twice a month ,I also take advantage of staples,Officemax promotions on the lower denominations Visa/Mastercard GC that they run from time to time but liquidating them are PIA,although I use them for everyday spend .

Yes the risk is there ,but I put other spend as well on the Ink cards not just office stores ,so do what you feel comfortable with.