I think the important point here is: 21 is an odd number. If you hold 4, for instance, 2 would go up and two would go down. Best to own 5, then you could have 3 up and 2 down but if 3 were down and 2 were up then you have to increase the number of stocks to 7 and hope you could have 4 up and 3 down. so on and so forth until you become your own best mutual fund and only have to beat some benchmark for bragging rights and losses are just an illusion.
I hold one ETF, which is EWZ, seven different accounts. Everyday, I concentrate on selling two accounts, then repurchasing. My purpose is to accumulate additional shares without adding new money.