Using fans to the point of rubbing leaves off, or scraping stems together to the point of injury to the plant is not using them correctly imo...while it's ok, even good, to run a small fan on small stretchy plants initially, once the stems have strengthened themselves and are sturdy it does not add much else....what you're trying to do with the fans is keep the air immediately around each leave provided with a constant fresh supply of co2 to grow with...stagnant air surrounding the leave equals slack growth, because the leaf uses the co2 up pretty quick, but you don't need to keep them in a wind tunnel for good growth either...it's more important to have a gentle circulation of fresh (outdoor) air, or add co2 to the grow than for the plants to be in a 40mph wind all the time. For a small grow, tent or closet, one fan should bring in fresh air, one should vent heat, if it is a problem, and one should be gently blowing over the tops of the plants to keep the fresh air circulating, not trying to blow them over...They just don't need that much airflow to grow well as long as the airflow is supplying what's needed to grow. Hope this helps!

My small closet grow uses one 5" (@ 120V, 0.1 amps) axial fan to bring in fresh air, circulate it once or twice, cool the light and vent warm air out as it rises in the room...it never actually blows air directly at the plants...I tested this one fan and duct system with a smoke bomb before I grew in it to see what I would have to do to keep a 400w HID lamp cool and keep my room cool and supplied with fresh air too and not use anymore electric than necessary. My total electric usage for growing (flowering mode) is just that...a 400w HPS and a fan that draws 0.1 amps, so it's virtually invisible to the electric co. what I'm doing.