How many non-web wallets discard private-keys? or How common are non-deterministic wallets? I'm concerned about non-web wallets that discard private keys after use.


Web wallets - share addresses between users, so the user can consider all private keys to be immediately discarded.
Deterministic wallets - All receiving addresses can be regenerated at any time and so it's impossible to lose funds that are transferred to previous addresses even ancient ones.
Paper wallets - are essentially permanent addresses, so no issue there beyond user-error.


So this just leaves me with the question of how many non-deterministic wallets discard previous addresses (including change addresses)?

It has been stated that "the BIP 0032 standard for Hierarchical Deterministic Wallets is used by all good wallets as of 2019.".  Should I take that assessment literally with regard to non-web wallets, that non-deterministic wallets are uncommon even on mobile?
None. No wallet that exists discards private keys. That would be superbly idiotic to do because that means that money could be thrown away permanently. No wallet would intentionally do that.