patterns are discovered on the water by determining where the fish are, what they are relating to, what mood they are in, if they are wanting to chase baits or sit on bottom. none of this can be found without fishing. I would also say you can have a general idea of where fish might be and what mood they could be in depending on the season, water temp, forage and so on but that does not set a pattern for any given day, it could be summer and they might be in 3 feet of water or they could be in 20 feet with the same water temp at the same time of day
To me junk fishing has a very simple definition as described by Gerald Swindle in a bassmaster podcast. junk fishing is not having a set pattern and fishing whatever comes up in front of you on the water. for example: seeing a laydown and throwing a spinnerbait or squarebill, seeing fish school and throwing a spook or fluke. It has also been described as fishing by the seat of your pants, pretty sure Tharp said that in an FLW if i'm not mistaken