I normally finish things in a few months. No more than 6 or 7, at the most:)

With skin care they often come in sets with a different product for time of application. In general your skin care routine might look like: 

AM:

Cleanser
Toner
Day lotion with SPF

PM:

Cleanser/makeup remover
Toner
Night cream with antioxidants
Any anti-aging specific products like eye cream or serums

Hope this helps! 

I have a hard time using up ANYTHING by its expiration date, be it cosmetics or food, LOL.  I have a small face, so maybe this is the reason when it comes to skin care products.  Even if I try to use something everyday to use it up in time, I end up having to throw it out due to its expired shelf life.

One thing I've never used up completely is eye shadow or lipstick.

I wouldn't slather or pile something on my face just to use it up though, LOL.

Sometimes I get tired of something & want to get something new, but I haven't used up my old stuff yet.  So, I try not to have too many of any one kind of product, but I get enticed into getting stuff anyway.....

Whatever works for your skin is what you should do.  If you don't need a lot of product to keep your skin healthy that's fine.  I would say try buying a smaller size in products so you don't have to worry about expiration date

I agree, whatever works for you! I tend to buy way too many products so I never use them all up, but every now and then I find a product that I LOVE and breeze through it in a couple weeks or months. If you really like a product, you'll probably use it all before it gets old/expires/dries out... and if you find that you always have a lot left over you should try buying a smaller portion.

I found this article about common makeup mistakes that was helpful for me, you may want to check it out!

Definitely only use as much as you feel that you need.  I have had the same thing happen to me with a moisturizer from Clinique, and when I tried to use more, it was too heavy and I did not like it as much.

Hope this helps!