After you have made 10 choices or reloaded the page, system drops all characters that you have learned, so then you start only with problem ones.
The quiz stops, when you show good results on every character.
Remember: you need to reach proportion of 3 «right» to 1 «wrong» to eliminate a character from repetition. Good luck!
All results are stored on client's side: if you change browser or computer, you run testing again from zero.