We almost never finish a bottle of milk before the date on the bottle and invariably end up throwing half a bottle away all the time.
With whipping cream it is a lot worse - I am always throwing half-used cartons away... cringing as I do so because whipping cream is rather pricey.. (and I do like to use the good ones.. somehow the difference is very noticeable to me.,)
I chanced upon this website and thought it very useful - http://stilltasty.com/.
It is a shelf-life guide and tells you how long you can keep stuff for before you really have to throw it out. The whipping cream one, for example, is useful for me because I thought that you can't freeze whipping cream. Apparently, you can.. only that you can't use it for whipping.. But it can be used for cooking.
A good website for those who think they need to throw things out less - that's me!