You're just paying more for less as someone already stated. It takes 8 drops per 4 gallons, which in anything larger than a 10, means you'll be plowing through that stuff in no time. I have a 10 gallon w/ a 20 Long sump/fuge attached to the tank, and i found it easier to just buy Kent's tech cb part A and B in the gallon jugs. I feel for my system that'll last a long time. Also as someone stated water changes WILL bring the alk/cal to balance (for the most part) but if you have a system demanding alot of alk or calc (or have trouble keeping it in balance) the bigger bottles and less dosage of those would be the way to go.
Stewie