Validity period of GPG-keys

[Jan Dirnberger]

Hi!

I'm working on a school project, including Public Key Infrastrucure (PKI).
We are instructed to get out how long the validity period of a GPG-key
should be set in a company or other organisations the info-material we collect
is for in.

First I wanted to advise a unrestricted validity, but then I remembered that
organisations or enterprises might have often changing memebers. So I'm caught
between the devil and the deep blue sea what to advise...

I tried to find out with Google, but there aren't any publications including
these informations.

Thanks for any advises or experiences!

Greetings,
Jan