Not sure if it's luck or skill, but of the over 220 apps I have in my SWDIST library, only three require a pre-copy to the local disk to work properly. All - as Les pointed out with his Cisco example - put a wrapper around the network stack and temporarily drop the connection. Two are the Cisco VPN and VoIP Softphone clients and the other is the SonicWall VPN client. The Cisco SoftPhone app will actually install OTN unless you need CDP and dual-IP capability, features which mess with the network stack.
I've packaged so many apps for OTN install, both internally and for clients, that I never copy files to a local system anymore.
Glenn
PS - I prefer to think it's "skill" 
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Actually I
am a Rocket Scientist!
