Board Thread:The Quarters - Q & A/@comment-83.83.240.111-20190321210301/@comment-25085701-20190322225351

Depends. If you want something that repeats every 3 days 3 days every time,  or every 5 days, 5 days every time, that's a piece of cake, because one of the options is 'Repeat Every X' days. If you want it randomly, 3 or 5, each time you check it off, that's a bit tougher. You could still make it happen on the day you check it off, edit the task to be 3 or 5 days out for the next time, and that should work.