Hi Guys,
The program cron (/totara/program/cron.php) has an hourly cron that does enrolments and a daily cron that does a whole load of other things including completions. There are a couple of things you can do to make completions run more often, but they are both code changes.
In totara/program/cron.php you can edit lines
#61 $hourlycron = 60 * 60; // one hour
and
#86 $dailycron = 60 * 60 * 24; // one day
so for example, changing the hourly cron to 60 * 10 would make it run every 10 minutes.
Though making the entire daily cron run more often could put your server under a bit of strain so if all you want is completion running more often I would recommend moving this line
#100 program_cron_completions();
from the daily cron to the hourly cron, say just under the line
#74 program_cron_first_login_assignments();
Hope that helps,
David