Well, that's a YMMV situation. Here's how I think of the problem without any nerdy physics or math. 
Heat rises. So you're depending on the heat from the chamber to rise up carrying with it whatever smoke fluid you vaporized. I compare it to the classic rotating lighthouse and the like where rising heat from a resistor generates just enough upward air flow to spin a lens or whatever on a needle-point bearing. So I suppose cranking up the heater power increases the smoke output in part because you vaporize more smoke fluid...but also because the hotter chamber will create that much more rising-heat airflow.
But the extra heat will also conduct thru the chamber into the caboose where the melting plastic phenomenon rears its ugly head. Hence, the addition of a fan. Just repeating myself but tiny DC motors are less than $1...
