Visual Studio keeps building everything

Question

I have a large .sln file with many projects.

I just made a change in project A and it builds nine other projects that project A references, but that had no code chan

Answer 1

This happens when a project has a file that doesn't really exist.
The project can't determine if the file was changed (because it's not there) so it rebuilds.

Simply look at all the files in the project, and search for the one that doesn't have an expandable arrow near it.