In Athenian Red Figure Vases of the Classical Period by Sir John Boardman, on page 19, the picture labelled [6] has on the top right has a man thrusting a spear overarm. On his left arm he has a shield that covers his shoulder to his hip, hanging from which is an apron that reaches almost to his ankle. It is more than 50% longer than the shield is round. I know that the figires are Gigantomanchy but other figures are carrying the aspis and they cover shoulder to knee. The pot is about mid-5th Century.
All the representations I have seen of the apron make it smaller (or much smaller) than the shield (including those I have on my rather beautiful 28mm Athenians with the same eye painted on the apron). Is this figure on the pot an artistic licence or have I always had it wrong?
It's longer than most examples, but I don't see why it shouldn't be accurate; sizes of these things may have varied quite a bit.
Compare the Amazonomachy in illustration 17 of the same book; there are three hoplites with similar floor-length shield-aprons - interesting that the two vases are of similar date. A lot of their length seems to be dagged tails, rather than a solid rectangle of leather or cloth, which would presumably be less clumsy and less likely to catch on things.
I would assume that for a taller man, having a larger than normal shield made could be more expensive, and getting more leg protection just by increasing the diameter of the shield could get heavy with a round shield. So it would be less of a burden to give him a longer shield apron.
Jim