3) The best way to counter an attack (and a lock could be considered an attack) is to short-circuit it in process. So even if a lock could not be broken once fully engaged, you must pay attention to the process of engaging the lock to be sure you understand at what point the process can be countered and seek to minimize the possibility of that counter within the process, not just at the end (I've found that many hoshinsul techniques an be difficult to work against once full engaged but often be countered in-process by an intentional roll or flip, orby a strike to disrupt the process or a movement that changes the angles/forces).
My last Hapkido instructor maintained that almost anything could be countered in-process, so you had to be ready to 'flow and go' into a new technique based on new positions, angles, and forces
That is exactly what I tried to say.
Is better to counter before is fully engaged, because once finished, some locks can't be defeated, or worse, the damage is already done.
With a lot of practice, you can counter most locks before they can't be unlocked, practice will give you the eye and fast movements needed to achieve that.
While I'm teaching ho sin sul some students often ask questions like "how do I defeat this lock?". (They demonstrate it)
Most of these locks can't be defeated once engaged.
Then, I explain "is better to learn how to counter in-process, before the enemy has defeated you with a joint lock" and "If you wait for your enemy to lock you, he will win"
I also explain to them if the enemy is not well trained (Street fights), he may neglect something and the lock may not be perfect, or he may give you a little chance to fight back, and you must learn how to unlock and escape, then strike back.
Both ways can give you a good self defense repertory.
Regards.