Shadowless flight requires the Boar handseal. You see the boar handseal, tho only taking a guess, you build up your raiton chakra, as you see that they perform that seal only and then vanish, you have enough intel to know that it's swift release so when they get to you, it would be close, but you would be emitting electricity from you. Yes it's cheap, but so is the opponent if he/she is trying to win that way. It's the Same as how people never look into an Unchiha's eyes before they fight, even tho they have no way of knowing they are an uchiha until they activate their sharingan. Taking precautions is a common thing. If they move around you, you simply, turn around? Since they aren't in your frontal vision they must be behind you. Unless you meant they just swift back and perform water, you stop the electricity and counter the water
When Hiruko starts fighting Naruto, he uses Swift Release to cross a distance that's definitely greater than 10 metres to slam Naruto with a Big Ball Rasengan. Swift release is also nature type chakra, meaning that it isn't excessive, it's your body using your chakra to go at fast speeds like gates basically in the sense that you would not have to stop every 5 meters to use it again, you could keep moving until you run out of chakra.