Recurring tasks which will take 30 minutes or more can simply be created as a recurring appointment in your calendar.

Otherwise, you can make the task repeat in Todoist:

  • Click task.
  • Click .
  • Type or copy and paste (be careful to highlight everything) the following text:
    • Recurring every day
      every day
    • Recurring every Monday, Tuesday, Wednesday, Thursday, and Friday
      every weekday
    • Recurring every week (starting today)
      every week
    • Recurring every month (starting today)
      every month
  • Click .

Learn more about date & times syntaxes on https://support.todoist.com/hc/en-us/articles/205325931-Dates-and-Times.