Arguably, once you are working on a sufficiently complex and mature system with good-enough tooling and tests and development practices, these edge cases can come to dominate. I don't spend time debugging simple things on their own, because the simple things on their own are generally well tested, so the failures that do happen emerge from their combination and integration into complex systems.
That said, I do spend a fair bit of time using a debugger as my first-line response to an issue - but overwhelmingly it's to examine a crashdump of the failure rather than investigate a live process.
Arguably, once you are working on a sufficiently complex and mature system with good-enough tooling and tests and development practices, these edge cases can come to dominate. I don't spend time debugging simple things on their own, because the simple things on their own are generally well tested, so the failures that do happen emerge from their combination and integration into complex systems.
That said, I do spend a fair bit of time using a debugger as my first-line response to an issue - but overwhelmingly it's to examine a crashdump of the failure rather than investigate a live process.