I often use Donetick for creating tasks to learn something on a given date. For learing I like to use the "spaced repetition" method.
This method describes, that learning in an interval like after 1 day, 3 days, 1 week, 2 weeks, 1month, 3months.. is useful. Hence, I currently create a task for learning something, and when done, I add the task again, but with the next iterations duration.

It would be nice, if there would be another kind of "custom" time to add, when ticking, that the task repeats. I know, that it's probably quite hard to store something like this into a db. I thought about it, and my conclusion was, that it would be good, if a user could provide a list of (hours/days/weeks).
Could look like this

• Select unit: [ ] hour | [x] day | [ ] week
• Iterations: [1,3,7,14,30,90]

what in this case would mean: repeat the first time after a day, the second time after 3 days, the third time after 7 days and so on. This way, no implementation is needed, of how spaced repetition works - since I am aware, that this app is for chores. But this is just my kind of chore.