[TYPO3] installing extensions -> global or local?

[Bas Heutink]

Hi all,

I have websites running with a shared source package (with symlinks).

Now I know that it is posible to install extensions in the shared source 
package (global extensions).
My question is what is more practical:
- installing extensions for every website locally OR
- just once globally, in the shared source package

Regards,
Bas