Yes, I understand the reasons to have enough dynamic range and enough headroom. My question is about what specifically is enough.
I think 16-bit quantization noise level is usually lower than the noise of all the analog hardware before the ADC, but 24-bit quantization noise seems to be lower than even the internal noise of audio ADCs so there seems to be no reason to go higher.
If we want the best quality end product, free from low-res artifacting, we need to preserve an excess of resolution all the way through production until the final export. Exactly how headroom much is enough? Enough that artifacts arising from insufficient resolution are not perceivable in the end product.