Say you have an application that needs to be compiled into multiple different variants, say a internal debug version with extra logging, or a version with customer specific functionality. You can use the Conditional disables structure to ensure that only required correct code is compiled into the EXE. By limiting what is compiled into the EXE, DLL dependencies can be removed, avoiding the need to ship internal only/customer specific DLLs or libraries with every version of the software.
Conditional build symbols are currently defined at the Project level in LabVIEW, and apply to all build specifications in that project. This means that you can't have two separate build specs for the 'standard' and debug/customer specific versions of the software, and instead have to manually change the settings between builds, introducing the possibility for human error, and making it difficult to automate all builds.
Any symbol defined in the Conditional Disable Symbols section in the Build spec would replace any symbol with the same name defined at the Project level. If a symbol wasn't defined at the Build Spec Level, but at the Project Level, the Project one would be used. When viewing the Conditional symbols for a build spec it would be useful to also show the symbols already defined at the project level, so that it's clear what is different and what is being redefined.
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) and make the BD a bit cleaner too. 
I get frustrated by having to search for items created on the front panel that get dropped in an almost random position on the block diagram and visa versa.
