Absolutely! When a child returns to a particular activity over and over, they are repeating the process, hopefully refining their understanding and their work.  Repetition does not just occur in a single session. It would be helpful to observe closely to ascertain why, or what seems to be a stimulus for returning to a particular material. 

Or what seems to distract them from one piece of material to which they later return?  What interest or need is being addressed by returning to a previous work?  Another question to consider is, “Is the child bored?” 

If the child has mastered a piece of work, they may be ready for something new.  Mastery comes differently to different learners and does not necessarily follow what was done in our training courses.