My missus has no sense of smell, try again,
mine dissapeared for 2 years, and while walking by the sea it suddenly came back, and the first thing I smelt was a fresh dog poo that had just been stepped in :-(
Ok that lost something in the translation, in other words slow flash is 50%, fast flash 80% and steady 100%.
but if you had that with LEDs you would get all sorts of patterns, at some time in infinity they would all flash the same !
I made a project about 7 years ago, with 2 chips ( before Arduino ) and 6 transistors, that could fade 10 strings of RGB LEDs at random through all the colours( they had crappy capacitors in the clock circuit so it was I guess random as the heat would never be the same through the box ? )
The colours could also be set manually with 3 pots, and the units could be cascaded and either synced, or all free running.
Each string could be wired differently - well 9 ? ways , so there were all sorts of combinations, but every few minutes, all 3 colours would be out for a second or so, and if you timed the interval, it was always a bit different. I have a couple in the drawer, I must connect one up again, it was very soothing.
If it had an arduino chip in it I would put it on playground !