Yeah, I throw a lot of pictures away on some tricky shots as well... (or rather I intend to but often don't get around to sorting out the good ones from a big batch I intended to sort through).
Ours goes higher as well (64000 or even 128000), but hubby has done some test with the lens cap on which showed that up to 1000 there was no noise, but higher than that there were specks starting to show in the black. He had read somewhere that this was a test of how high you can go without degrading the image. So now we have set the auto limit to 1000 to ensure we have to manually choose to go higher.
You still have to get the camera as still as possible and take lots of shots of course before you get the good one.
The more I learn about the photography the more I'm in awe of people like you who get such great shots