When my bonsais were babies, I tried grouping some by 3s. See how it would grow. Well now they have grown and it is getting crowded. The plants are less healthy than the twos or the singles. And the roots are not expanding as fast as the doubles or the singles. So today I took out one to give the remaining two room to grow. Now I know, three in a pot is a bad idea.
Much like life, unless the third is the offspring, three in a setting is difficult to maintain. Growth in each one is cramped and potential is limited.