In my opinion if you practice the air dummy i would suggest doing it slow and soft as well as fast and hard. Practicing both ways can help you with muscle and mental memory and programming. Also while doing so slow in the air it allows you meditate on the moves you perform while performing the action. Now some will say it also allows for yin chi develop. I think practing the dummy in the air is akin to practing your punches in the air. You should have a wall bag or heavy bag to do your punches on but practicing in the air provides basic benefit.
Now some people only hit the dummy light or work around it. I personally believe the dummy was designed to conditioned your arms so you can take impact when someone crashes against your arms. So one should practice the dummy hard an bang the wood with force with the use of dit da jow and also practice the wooden evasively with less force to work on technique and accuracy!
IMHO i think the Air dummy is beneficial, Along with that I also believe once you have mastered the form of the dummy you should begin to freestyle on and off the dummy with wooden man techniques!
The Flow is relentless like a raging ocean with crashing waves devasting anything in its path.
"Kick Like Thunder, Strike Like Lighting, Fist Hard as Stones."
"Wing Chun flows around overwhelming force and finds openings with its constant flow of forward energy."
"Always Attack, Be Aggressive always Attack first, Be Relentless. Continue with out ceasing. Flow Like Water, Move like the wind, Attack Like Fire. Consume and overwhelm your Adversary until he is No More"