Probably not. I've seen this chart in multiple geotech companies. It probably gets pointed at a lot when another contractor goes "but this is obviously sand!"
The lines to follow are the ones at the angle that the little arrow points. Which is 'down and to the right' from each side if you put that side on top
Somehow I'm bothered that Sandy Clay Loam and Silty Clay Loam are both a thing, but Loam is already the "Silty Sandy Low-Clay Loam" and a the middle-most area is "Clay Loam" instead of pure loam. WHY IS CLAY'S POWER SO GREAT!?
Is this what keeps the soil kingdoms in balance? The two rivals, silt and sand, locked in eternal hatred and yet forced to cooperate to maintain balance against the all consuming Clay Empire?
Areas with loam touch all three sides. So... Some kind of loam exists without sand, some without clay and some without silt. I am not a soil scientist but I'd guess that any substance that contains neither is a kind of loam.
Man I've gone my whole career without ever dealing with this BS. We use USCS. One time my boss had to deal with it because of some permitting shenanigans with an agency (USDA?) and he said it was stupid.
It makes more sense if you use it as intended. It's designed to be a simple way for farmers/gardeners to classify the basic soil composition by particle size.
Take a cup of dirt, put it in a mason jar, fill it full of water, put a lid on tight and shake the hell out of it. Come back in 3-4 days and measure the layers.
This comes in helpful in applying pesticides and basic water management. It's pretty much pointless for anything else.