Test cuts on owl faces

[manpace]

I find it interesting that so many Athens owls have test cuts marring the coin's major features - particularly the owl on back.

I've read commentaries that suggest this was done for spite, defacing the symbol of Athens.  I'm sure there could have been an element of that, however, wouldn't someone be inclined to cut on the thicker parts of the coin, so that the coin was less likely to break in two?  And there's not much thicker than the owl head.

http://athenianowlcoins.reidgold.com/Classical_fouree_test-cut_in_test-cut_r.jpg