I noticed CM does not offer this feature in the standard web app. to send emails. You can schedule a campaign, but not set up a reoccurring campaign (ex. send to the list every day).
Can someone confirm, the best way to handle this is to build an API to trigger a template mailing at a set time interval or event?
Yup, you could use the API for this. Setup a couple scripts (PHP, .NET, Ruby) and trigger them to be sent via a cron or scheduled task every day. The content can be pulled via a URL so you can even make the content unique for the day.
It's probably best to take a peak at the APi documentation to see what's possible:
The alternative approach (from the app) would be to just schedule say, 10 campaigns at a time (2 weeks worth) and then every 2 weeks just schedule the next 2 weeks worth etc… etc…