Reciprocation - Returning Others Help

If we are getting help from someone, it is minimum courtesy to return atleast what they have spent for us, be it money or time. For big personalities, it may be difficult to return either in the form of money or time. Because, the big personality may be earning a lot per hour, and may be able to do a lot in one hour of his/her time when compared to others. If that person had spent one hour time for us, returning in any form would be very expensive. At that time, atleast if we do their monotonous/inferior tasks, and free up their time, it would be equivalent to repaying what they had spent. If they directly ask in helping their monotonous tasks, and if anyone rejects it because of the inferiority of the task, (without repaying their help by any other means), it means, they don't have any courtesy.