A 1 hour server certificate might work if all clients had the proper time set and all libraries were comparing the notAfter to the UTC current time.
Sadly, lots of phones and computers have incorrect time settings, off by one hour to work around incorrect DST settings is pretty common, off by several days isn't super rare either.
I have run into some SSL client libraries that check notBefore against the current time, in the current timezone, and therefore those in the western hemisphere would fail to work for several hours after a certificate was issued. I imagine they're using the same for notAfter, so those in the eastern hemisphere would stop working early.
My rule of thumb is a certificate that is less than 30 days old or has less than 30 days of validity left is going to cause problems for a subset of your users, and shouldn't be used unless you have a good reason (old certificate compromised would be a good reason).
