If you happen to be making a Block from sketch entities, dimensions and notes created on a drawing sheet, BEWARE!
As you may have noticed, often (as the Block is made), the scaling of the dimensions, arrowheads, leaders and notes can become a visual mess with unintended overlaps and skewed proportions relative to the sketch entities.
This, unfortunately, is due to the scaling of the drawing sheet being set to other than 1 to 1.
The moral of the story is to be sure that the sheet scale is defined as
1:1 before spending time carefully laying out any detail which is intended to become a Block...Per O. Hoel