How do you keep the keys apart...?
For many years I have lived in the heart of the Dutch city of Groningen. Not only is it a beautiful city, it is also the cyclist capital of the world. No less than sixty percent of all traffic movement there is done by bicycle. And so yes, lots of bikes get stolen, too. So, I have become somewhat of an expert in the field.
But both 1. and 2. are not a guarantee against theft. Cordless angle grinder fit in a backpack and cut through any lock in less than a minute.
The safest method is what I do myself: I never take a lock with me! It prevents me from fooling myself that I can safely lock it. When I visit a café my bike stands next to me. When I buy some groceries I try to find another biker to watch my bike and take turns in shopping. It’s a bit cumbersome but the absolute safest way and the positive side effect is you don't need to carry a heavy lock with you anymore.