I understand not all private keys 256-bit numbers are usable as private keys as they fall outside of Secp256k1 ...
FTFY
According to BIP-32, which is really what you are asking about:
In case parse256(IL) ≥ n or ki = 0, the resulting key is invalid, and one should proceed with the next value for i. (Note: this has probability lower than 1 in 2127 .)
Thanks! Your correction is definitely precise.
About the line you quoted from BIP32, I am familiar with that, but how does it matter unless the child in question is of depth=3 in BIP32? What happens when such a case occurs in depth<3? Are we supposed to ignore it by standard or there is actual merit to it that child generated under that branch would be all invalid keys only? I think its the former, but not sure.
Skipping the account itself (depth=1) or wallet chains (depth=2) when that particular child falls outside of the acceptable private number range, sounds silly. So that's essentially where I am looking to get more clarity.