A lot of my students like to repeat my lessons over and over again.
And I recommend that for the majority of students.
I personally believe that the more grounded you are in the basics....
And the more fun you're having (sometimes people have more fun by not over-challenging themselves).... The more likely you are to fall in love with the harmonica and play it for life.
Some advanced musicians may be able to play through a particular lesson once and then they're done with it. I leave it up to you to find whatever way of practicing works best for you.