check-updates and download-only

Hi all,

I want to prefetch updates.

I thought about something like

   for PKG in $(yum check-updates)
   do
     yum --downloadonly ${PKG}
   done

On a nightly basis (a cron)

Then in the morning, if I run the "yum update", only few things will be 
downloaded (the updates newer than the cron launch).

Is it a good enough practice? What would you advice to make it better?

If needed it's to be used on a CentOS 6.2.

-- 
RMA.