I have encountered rattlesnakes in my work as a orchard field man. They have always given the rattle as a warning. I just agreed to move out of their way. Usually they then slithered off and I was happy to let them.
The problem with rattlers is when they’re shedding. Their eyes are clouded from the loose skin and they will strike before rattling as they can’t tell from visual cues and use their heat receptors only and strike ‘blindly’ in the direction of the heat source.