Not a problem. I routinely bring between 12-20 cans for my family, depending on whether or not we're doing beach time.
For the poster who asked if a single adult would use 6 cans in 11 days --yes, certainly, especially if there are full outdoor days planned. Each 6 oz can is good for 6 applications for one adult; about one full day's worth if the entire day is spent outdoors in contact with water. (It's recommended to reapply every 90 minutes if you are swimming in full sun.) Sprays also tend to lose a bit with wind-carry, so you go through them faster.
The ACS suggests that for proper coverage, an adult should apply at least one full ounce at least every 2 hours. One ounce is a shot-glass worth if you are using lotion, or one-sixth of a six-ounce spray can.