expiration dates

I don’t understand the size make-up comes in for its expiration dates. Most eye make-ups are “good” for 30 to 60 days. Mascara, for example is supposed to be tossed after 30-days. To be honest, I for one continue to use it after 30-days. But anyway, the size mascara comes in, the 0.25 fl oz tubes, are impossible to finish in 30-days. I use it daily, but it’s never enough to finish it. Am I supposed to recoat mascara 6 times a day to get my full 30-day supply in 30-days? They should just sell mascara in smaller tubes at half the price.
Same goes for eye shadows. I’m sorry; I like my variety of colors to choose from. Eye shadows come in pretty large cylinders that take months to finish. And using an array of colors… never will I finish a color of eye shadow before its expiration.
I guess my question is; do people actually throw out make up as often as they’re supposed to? Or do you continue to use it until a. you feel it has become old; b. you finish it. Also, does anyone actually finish the make-up before it expires?