I always keep a few rolls of duck tape around. It is useful for a lot of temporary purposes. It will simply not last when used on duct work.
I remember my Father bringing some sort of tape home when he worked at Eglin AFB. I think it actually had a metallic backing and probably would have worked for permanent uses but regular duck tape will not.
Instead of arguing with me, why don't you ask the next a/c guy you meet, whether or not they're familiar with this?
What you think about the properties of duct tape is irrelevant. It's been used for decades for the exact purpose I described, which is how and why it got its name.