I just dug out my foundation from last year and it's half full. It's the YSL Touche Eclat, the old formulation.
I use foundation over the winter and tinted moisturiser when I'm tanned. So, one tube of Just Skin and one bottle of the YSL last me for about two years, half one season and the other half the next. I do use something pretty much every day.
Moisturiser - one pot of cream, six months or more.
Facial oil, six or seven months.
Am I using them too sparingly? How much do products last you?