Hi Rich,
Yes, you're right - the corner joint is also hidden!
Next time, (on the next layout) I will use radius corners! However, in this case, the depth of the boards and trying to get the buildings as close to the corners as possible, it was not very feasible to radius the corner.
Also, at the other end of the layout, where th bridge runs across as scenic break, having a radius corner just would not have worked.