You don't need to run for more than six seconds unless you buy a defective feeder that doesn't throw properly; any normally-operating feeder will throw a lot of food in six seconds.
As noted by others, you get what you pay for; it's easy to gloss over that and not fully believe it, but your fish growth could vary drastically from Aquamax to an inferior food. Think of it as trying to grow cattle on good hay versus feeding them cardboard. They don't get much nutritional value from the cardboard, so they don't get as fat.
I would suggest as a cost-saving alternative to just feed less, rather than compromising on food quality. I'd venture you'll get more growth from Aquamax once a day, or maybe twice a day for four seconds (plenty if your bluegill aren't overpopulated and you forget about the catfish), than you would from a cheap food twice a day. Just my $.02. Also keep in mind bluegill stop feeding on pellet food around 54 degrees for water temp, so you will have at least four months or so in the winter when you're not feeding at all.
