How can I stop repeating by a specific time

dismory says:
For example, I just want a task repeat 3 times or 2 days, how can I do that?

davidscottweaver says:
Interesting. How about if I want a task to repeat every few days for x times, but don't want the tasks to "build up". I tried putting "after 3 days for 20 times" but RTM didn't seem to like that.