I smoke with a low temp and try to keep the box cooler for salmon, so it can be a bit harder to get the smoke going like that. The fan pulls the air and helps with the smoke to continue. When it’s cold outside it’s not as hard to maintain a lower temp and longer smoke. But what I normally do is feather the on/off switch and use the fan to keep the air circulating to try and pull the smoke. I don’t want to cook the meat quick, so low temp, but need smoke. I’ll also use chips for these types of cooks, so air circulation helps with the fan.
And for the sausage (talking homemade sausage) it’s even more important so you don’t melt the fat. So same process as above. It was a cheap investment for me and has worked well. I do have a few eye of round in the freezer I should try to make jerky out of.