The iD L growth has nothing to do with catching their poop. The growth system is based on care misses. However, there are unexpected growths that come from picking up three or more poops while your iD L is a certain teenager. It applies to Painaputchi and Hanikamatchi. If you do pick up three poops or more while they are teenagers, no matter how many care misses you give them, they will turn into Lovelitchi and Mametchi, respectively.