I reached out to the Install Policy experts and got this out:
The “Finalizing Installation” phase is when we update the log server with the resolved objects, so that logs will show Check Point objects rather than IP’s, ports etc.
Technically, by the time you see "Finalizing...", the policy is already applied on your gateway. This is only a completing step for the sake of logs data.
Few things that I'd like to point out:
Perhaps the 99% delay is the SMS putting/committing a copy of the successfully installed policy into the "Installation History" list of the SmartConsole
One word which we no longer use in R80 is "copy". Things are pointed to, not duplicated. The Installation History is simply references revision ID's which were sent to a Gateway. I know that when we sell R80 Management we start with the things which are easier to explain (multi-admins, publish mode, locks) but I am hoping with this community we'll be able to discuss the hidden architectural benefits in more detail.