[londons_explore]

If you never reuse an address, all of this concern goes away. Spending any funds from an address means spending them all, and then any private key leaked no longer matters.

[RL_Quine]

That's not actually true, as most private keys are deterministic produced. Leaking one key from a HD wallet leaks them all.

[poontang1]

Leaking a single private key does not leak all the private keys. You would still need the chain code used to derive all private keys, no?