Use of Signature

Thought I'd post a few thoughts on signatures. I know some of you sign and catalogue your work as soon as it's completed but I wait until I'm satisfied with it and it's mounted and/or framed. It's only at this stage that I sign it which is why many of those I post in the gallery have no signature. If I decide it's not up to standard I will either destroy it or paint on the back - don't we all do that? Not such a bad thing given the costs of paper these days! Another point here is that I do play around with mounts until I am happy with them - the placing of the mount can make all the difference and this alone will determine where the signature should go. I have, in the past, signed a work first only to find that when I'd decided where the mount should go, the signature ended up floating in space. As for the signature itself I often use it to balance the composition. For example many of my works seem to be weighted more to the left and a signature in the bottom right can make all the difference. I do vary it though and I've currently got a couple of pictures in a local gallery where the signature is in the left hand corner. I do generally keep it at the bottom of the painting although I've seen examples of signatures at the top of the work - but it always seems to be close to the edge which prompts me to ask why? If the opportunity arises I might try placing it in the middle if it helps with compositional balance - might prove interesting! Why is the use of a signature as an enhancement to, or as part of, the composition often overlooked by many artists?