I would say coupons! It is so hard to accommodate all the couponers especially if expired or manufactured etc.
I worked for CVS Headquarters in Rohad Island as windows team Build and the big challenge for me was that you feel you are working in Indian owned company. And its process is very complicated .
I have always found that the biggest challenge has always been staffing , especially when taking over a new store and you inherit someone else’s employees with bad habits . Usually within a month or two of holding people accountable and following processes we need to hire a new staff . When the new staff train them how to do the job properly we find it drives numbers , and those employees climb the ladder .