The drop knee turn is a stall turn as is any back foot weighted move. The drop knee is to give back leg extension and weight over the fins, The idea is to lift the nose and swing it around the board slows down in the process , regaining your upright stance and placing forward weight will give acceleration.
A plain wall stall without turn can set up a barrel or a nose ride. Back weight as strongly as you judge right hold nose up as board stalls. Move forward either to crouch for barrel or cross step to the nose as a reward.
Look on YouTube drop knee surfing!
Long boarding is about different positions on the and using them like a keyboard to play your surfing tune!

I've taken up troll hunting just for fun, instead of a rifle I'll just use a pun! 冲浪爷爷