Parallel for me.
Let the fish tell you I have caught them both ways
Ledge fishing is about the only way I can catch crappie. I fished 4 hours yesterday and had 28 crappie with 14 keepers. The ledges I fish are rock ledges on bluffs and points. I do not cast. I drop the bait straight down and try to fish it about a foot off the bottom. I use braid and 1/4 oz and heavier heads. I am using 2d sonar. Once I find fish I keep the boat in that depth and move along at .2 to .3 mph. Rarely do I find fish at more than a 3 foot depth range. Yesterday 25’ was the magic number. The last time it was 27. I only fish homemade plastics.
Not many ledges and such down here but in TN there was lots to choose from. One that comes to mind was only a foot tall but held fish on sunny winter days. Set up deep and cast shallow. That was good fun.
As Dwayne said, in cooler temps they hang out at a certain depth and don’t move much. Used to fish timber in 55fow about 30 to33 feet deep. Hi vis braid tied direct to 1/4 oz brush guard jigs and once the happy spot is found, mark the braid with a sharpie. Had a few extra stellar days doing this.
Creativity is just intelligence fooling around