The dbt runs at different times during the hour, rather than only at the set time.
To make it run every 55th minute, please change the setting to
55 * * * * . This way, the transformation will run on the 55th minute of the hour, rather than after the 55th minute of completion of the previous run.
If cron is set to
*/55 * * * * , the transformation will run in the following timing (i.e., every 0th minute of an hour and 55th minute of an hour).