random occurence of gongs

could you add "random gongs", for the intermediate gongs in the free meditation section. Let me explain, if for example I want to meditate 20 minutes, and I would like to add let say 4 intermediate gongs ( to bring me back if my mind starts wondering ), then I will know after each gongs how many times there is left, and I think it will be better if these 4 intermediate gongs could be at random times ( not every 5 minutes )