Bro, one advice from a seasoned car detailer, no matter how strong ur spray or jet is, it's still best to have a wipe down from a plushy microfiber towel full of soap.
Why? Because the MF cloth would actually really help to catch up all the dirt.
High pressure would be good for stubborn bird ******** that u dun wan to dirty ur hands and use tissue and clean. But other than that, stains that have seeped into the clearcoat, definitely you have to use the cloth and clean them off. High pressure ONLY cleans off SURFACE dust and dirt particles. NOT stains which have alr set into the paintwork which needs the soapy cloth to go over. (:
Why i say so? Cos i tried high pressure before @ petrol station. Came home, i wash the car again, cos the stains are just still there (:
my 0.0000002 bahts worth.