I have studied as well.(MA art history)...and the "rule of thirds'' has its place , i agree.....but some photography/art...whatever.... is also subjective "taking place within the mind and modified by individual bias".
As you said Adam....work it untill it looks right....whatever that may be. I do my screens to please myself....i share them , because i want to. Im not looking for anything...Im not making any statements....Im taking an electronic "photo" of an electronic image and Im working within the contraints of the media i have at hand.
These debates are always interesting.......Ive learnt a lot by doing these screenshots......looking at Gavins photos, other screen shots......its so interesting to look at what other people present....and every single thing has merit.
I have learnt to dislike critics and experts......critics (in my opinion) are worthless......refer, the defintion of subjective....and experts...well, x is the unknown factor, and a spurt is nothing more than a drip under pressure.
Point in case, a very famous(Modern) painting once hung in the louvre in Paris for almost 6 months before anyone noticed it was upside down...

....subjective....
Maybe Im a little to 70's in my thinking........but thank you for moving this subject up a level Charl
Marty