When I was a white belt I thought the key to having a good guard game was to lock on and hold guard no matter what. Now that I’m a black belt I’ve come to believe that making your guard impassible is less about locking down and more about knowing when and how to bail out when you feel your guard is getting passed. If you can prevent your opponent from securing a scoring position (side control, knee on belly, north/south, mount, back take), then you can make your guard impassible.