Ok I like inquisitee minds. You observed and learn some important facts. In general you are right about perch and crappie. Only the shadow knows. lol
Only us old folks remember that show. The further the shadows are from the bright spots (or fish} tell you that they are not on the bottom. All of those pics were in the mega frequency. In the last two pics the fish in the right if I remember correctly were in the creek channel. I think that is why the long lines. Now what can I learn from that. If I wanted I can go to those schools and drop a perch jerk setup and get a sore shoulder. I have seen video of some who use side scan to find schools of crappie get over them and cast jigs into them. In this case take my spoon and drop down most likely catch perch but could get some crappie.
Footnote: spotlock comes in handy for this.
I am exploring the different methods to catch perch and crappie. This is not about for me trying to find the perfect method to catch 200 fish each time. It is about learning and enjoy what you are doing.
I would rather fish with a friend laughing and cutting up catching 20 than out alone catching 100. I hope this helps some and I am in constant learning so no expert here.