The commit that Fedora Dev’s initially wanted to upstream to systemd was 15 seconds
Systemd devs asked them to not make such a drastic change but first try a step in between but the upstream pull request somewhat stalled then.
They seem to test the 45s in Fedora and check if users report issues - if not they will certainly lower it further or try to upstream the 45s - let’s see how they decide and what the systemd devs decide.
well:
But apparently, there is even another approach for those services, taken from the Fedora-Wiki:
Our users shouldn’t have to randomly sit waiting for their machine to shutdown. It will also encourage the correct use of shutdown inhibit APIs.
If the services would use those “correct […] shutdown inhibit APIs” the issue would also be a non-issue.