Lightroom: JPEGs Quality vs Size

When exporting JPEGs in Lightroom, you can set the quality of the output. It ranges from 0 to 100.

1. From 0? What the hell is a 0 quality? It turns out that Lightroom cheats. The 0 quality of a JPEG in Lightroom is not a 0 quality. It looks very similar to a 40 to 50 in Infranview, a free, as in free beer, Windows image viewer. The file sizes are almost the same size.
2. I can’t see the difference in photos between a JPEG quality of 100 and a JPEG quality 50 for a small or medium size photos ie: less than 800 pixels wide!
3. I can’t see the difference in photos between a JPEG quality of 100 and a JPEG quality 75 for larger photos ie: around 1500 pixels wide!
4. Photoshop “Save as JPEG” has 13 steps only: from 0 to 12. These look awfully similar to Lightroom. Look at the file sizes. A JPEG quality of 100 or a JPEG quality of 99 or 98 are the same size, the difference is only 0.05%.
5. I can’t see the difference, between a quality of 100 and the quality of 90 even at 1:1 preview but the file size is 29% smaller! Factor contributing: eyes, the video card, the monitor, distance …

File sizes

JPEG Quality	File size
100	7432kb
99	7432kb
98	7428kb
90	5276kb
75	2910kb
50	1151kb
25	396kb
0	79kb