[kh99]

Scheduled tasks will only run when your site has traffic, so if you set it to run once per minute, it will only run that often if you have continuous traffic on your site.

Also, I believe the promotion scheduled task only promotes users who have been active recently (the past 24 hours, I think). But if you run it by pressing the "Run Now" button, then I think it will pronote all users who meet the requirements.