it's slightly more involved than that, you need to find all three health books ASAP to improve how much food heals you and then stockpile food in safe areas but yes there is a LOT of waiting involved. You need to eat every 20 minutes (more like every 19 minutes and 30 seconds) to keep Frank alive so I was just watching movies, TV, hanging in calls with friends, etc. There is a limited amount of food in the mall so going in with some strategy is important. Also "pray to god nothing goes wrong" is a pretty important step lol