Personally, I believe that spritzing is completely optional...the reason I say this is because I prefer to leave my meats along while they cook to avoid losing temperature in the smoker, thereby slowing down the cooking process, which is pretty long for us low and slow folks already!!!
Every time you open that smoker you lose valuable cooking time and temp.
Spritzing = completely optional...
Now that everyone has voiced there keep the door shut opinions, let me say I have spritzed. Why? Because I wanted to make sure that everyone that dropped by got to see my good looking meats cooking without appearing to be a show off. "Sure guys I'll take another beer, hold on a minute while I mop the meat", "Yeah they are lookin guuuuuud, aren't they!"
That's why I spritzed/moped. AND I won't say I will not do it again either! Is it worth a 10 min addition to cooking time? Sometimes, you betcha!