For the most part, healthy snakes in proper setups don't frequently soak (with the exception of swamp snakes such as anacondas, bloods, brb's, etc). Some snakes will soak when they are approaching a shed, though I find many do not. Some reasons that a snake may soak are to ease the discomfort/drown mites, cool down, hide (if there are no other places to do so), or if humidity is too low. I would take it as a good sign that your Argie isn't soaking, this just means he has all his needs met and is comfortable