Cache; Is it even working or is it just waste of HD space?

Hi.
I am not happy with the caching, it seems to me it hardly works if it works at all.

I frequent several spots and see a lot of the same people.
How come SL always seems to have to DL the objects, textures and clothes again when i get back somewhere ive recently visited or seen.

e.g.:
It would seem to me that all the textures at my home location would be in my cache because i am there quite often. I'd think that not needing to get the stuff that remained the same from SL servers would proof to be a good time and resource saver.

Is it just me or is the Cache indeed not performing in a way that you would expect?

it doesn't seem to work very well.

I'd like to know what it's purpose really is.

It does disturb me that I have a 500Mb cache and yet I can flip back and forwards between two locations and all the texures have to reload, seemingly from scratch.

It would probably be useful if someone could tell us how it;s supposed to work.