I just figured how to stop projects to build the entire engine again instead of just the project binaries by reading GenerateProjectFiles() and IsSourceDIstribution() at DesktopPlatformBase.cpp. It checks for a txt file in your engine directory. The fix consists on:
- Renamimg [YourBuildFolder]\Engine\Build\SourceDistribution.txt to InstalledBuild.txt.
- Generating Project Files again in your game project directory.
Now the generated .sln files are similar to the ones in projects assigned to Launcher builds. You can Build or Rebuild your projects without any fear now.
Thought I’d leave this here since this has been asked plenty of times since 2014 and, as usual and AFAIK, nobody cared.