Build server/shared assemblies: mapped drive or UNC?

When reading about build servers and sharing assemblies on the network (for assembly references in projects), I have always read that the preferred way to do this is to designate a drive letter, and use a login script to map the same drive letter on all development machines.

It seems as though there was some reason that a drive letter is favored over a UNC path, but I cannot remember why. Can anyone remind me why I shoul开发者_运维问答d favor a mapped drive over a UNC path?

You need the drive letter so the debug symbols actually work.