I wouldn’t say the NTSB thoroughly investigates every small GA crash. There are quite a few where the they don’t even go to the crash site and just do it via phone interview. They’ll send investigators out when there’s something to learn that might affect airworthiness of the other existing aircraft of the same make & model. But if it’s fairly apparent that the pilot just fucked up, they often don’t send investigators out.
I wouldn’t say the NTSB thoroughly investigates every small GA crash. There are quite a few where the they don’t even go to the crash site and just do it via phone interview. They’ll send investigators out when there’s something to learn that might affect airworthiness of the other existing aircraft of the same make & model. But if it’s fairly apparent that the pilot just fucked up, they often don’t send investigators out.