while spritzing every 20 minutes may be a little too frequent, i'm not sure you can atribute the 7-hour cook time to that alone unless the dome was open for an extended period of time. the motto "let it cook and don't look" is a pretty good way to go if you're comfortable with your cooker.
Those look awesome! I always dry rub, have never foiled, and stopped spritzing a few years ago. And always hope they turn out looking as great as those!