Have you ever tried to spot a warning in a large project with hundreds of files? It's nearly impossible as all those build commands fly by. Note that I'm speaking to a more traditional Unix Make environment. Therefore, it's easier to fail on that specific file than to let the build continue.
Certainly building with a tool like Xcode makes the warnings more conspicuous, and you can just choose to fix all warnings. I don't see anything wrong with that approach, but I still prefer to just treat the warnings as errors. I guess it's just how I'm built.:)
When I build a program with make, the warnings are very easy to spot. While you do, without warnings, see a bunch of text fly through the screen, all of that text looks incredibly simmilar. Warnings (and errors) stick out in the wall of text.
I guess we've just had different experiences. I can say from experience, without a doubt, that I could not possibly pick out a warning among hundreds of compile/link commands.
Now, if dependencies were in order, and I'd just made a small change to a single file, and had previously built the project successfully, I'm sure I could probably catch a single warning. That's a lot of assumptions to work from. I prefer to let the build fail.
Certainly building with a tool like Xcode makes the warnings more conspicuous, and you can just choose to fix all warnings. I don't see anything wrong with that approach, but I still prefer to just treat the warnings as errors. I guess it's just how I'm built.:)