[gentoo-hardened] Updates: a way too simplified security question I am asking anyway

[Jan Klod]

Hello,
some people in gentoo forum made me ask this one: it is supposed, that regular 
updates of system is a wise thing to do, but, excuse me, ... those bugs and 
holes are there before someone say "update them" -- so do you agree, nowdays 
Linux is never safe?
OpenBSD has its own slogan about only very few remote holes in long time -- so 
it makes an impression, I can install an OpenBSD machine and let it do it's 
job. 
Can anyone crash my impression about OpenBSD (and is it still alive enough, by 
the way?)?
How about hardened gentoo in this regard (create system for few, specific 
purposes and leave it for years without damn update hustle)?

I realize, this is "in general", but the question is about software writing 
style (think when write it or wait for someone to find what is wrong) and 
ways to protect from bugs (like overflows etc) in software.

In ideal world, updates are necessary only to get software, that has new 
functions -- do we seam to approach it?

Jan