[CentOS] Multiple system updates

This is a question for you guys out there that have a bunch of similar 
configured systems out there... How do you handle your updates? I do not mean 
the technical level, but from the logistics. No updates? Just run yum by cron 
and grab the latest of the web and trust the developers that it works? Deploy 
only certain packages automatically (i.e. omit kernel updates)? run your own 
yum/apt/up2date/whatever repos? 

Thanks for your time,

Peter.