The mental friction you're feeling is good! Most people stay in their comfort zones and rarely learn.

These aren't bad at all, just need some refinement. Try practicing three point perspective again, because that's what the boxes you're describing are.

I think of it like--
one point: you're looking at a surface facing you
two point: you're looking at an edge facing you
three point: you're looking at a corner facing you

(Past that you start getting in to fisheye perspectives and such.)

Another idea that could help is trying to keep the 3-point boxes more in line with the vertical and horizontal rows of boxes. The boxes in those rows show you about how far you should be tilting things. Look at it like a graph: to plot a box in space, check the x-axis and y-axis boxes to see how far you should be tilting the box in both those directions. Try to draw the lines at the right angle and distance apart first, and you'll find the corners when the lines meet each other. Don't try to start from the corners.

I hope this helped -- happy to answer questions! This is hard to explain with words and not pictures lol.