The 3.14.0 release of Scap (current version) added the
--canary-wait-time option to the sync subcommand (which the next
version of Scap will rename to sync-world). This sets the time how
long Scap waits for code to run on canary servers. The default is 20
seconds, but if that is too long or too short, you can now adjust it.
As usual, please use carefully. Don't shorten the time just to make
your deployment go faster.