Grow Box venting and smell question?

I am reconsidering a few things about my build after reading some interesting articles here on ventilation, but my setup has plans for maybe 4 plants at max, but for the most part growing only 2 plants between both veg and flowering phases.

With only 3 plants should you still use a fan blowing inside the box and a fan blowing through your intake to circulate everything? The area is enough room for two large cannabis plants. Not sure if that would be to much air.

As for the smell, would it be skunky with that little of a setup?

yes you should still use an oscillation fan, no matter how many plants, it helps blow the hot air away from the plants, also helps strengthen them, stops mold/pests as-well as other things, you dont need a fan bringing fresh air in, as-long as you've got an out take just use a passive intake.

What about the smell factor? How long should a fan be turned on? Thanks for the advice so far!

You are going to want some type of scrubber.
We grew 1 kushage plant that stunk out the entire 12 plant garden all by itself.

My oso fans come on with the lights. Helps the plant build strong branches..

scrubber? Will an air purifier work near the grow box?

I wouldn't want to say no, but wouldn't take the chance either.

an air purifier will not work!

Id spend the money on a charcoal filter, worth it in the end