Anchor first, then fill
Place the largest piece before anything else. In the anchor layout the 16 x 20 sets both the centre line and the width of the whole block; the 8 x 10 frames beside it and the 11 x 14 pair beneath simply extend that shape. Reversing the order, filling first and squeezing the anchor in later, is what produces lopsided walls.
Two rows need one alignment rule
When a five-frame set breaks into two rows, decide what lines up: the outer left and right edges, or the vertical centre. Pick one and hold it. The planner's align and distribute tools apply the rule to the whole selection at once so the two rows share a boundary rather than drifting.
Row of five arithmetic
Five 8 x 10 frames at 2 in gaps measure 5 x 8 + 4 x 2 = 48 in across. On an 84 in wall the first left edge sits at 18 in and each following left edge advances by 10 in. Because every frame is identical, one hook height serves all five.