While I do use timers occasionally (mainly when baking or pressure cooking), I’m surprised to learn that people will set multiple timers just to caramelise onions.
I find that for most cooking tasks, sight and sound are more reliable indicators, and in many cases, the food will need to be stir or flipped so as not to burn.
Caramelizing—truly caramelizing[0]—onions is a slow process that takes close to an hour. For this kind of task, I think it’s helpful to be able to set timers and be in and out of the kitchen, rather than be stationed at the stovetop continuously.
This is semantics but I thought I'd chime in anyway. I don't think they were setting multiple timers, they were setting one timer multiple times, i.e. adjusting a single timer after doing said checks.
The gist I got from this poster is there is a lot going on in their kitchen at one time. They may have simplified the post to make a point? But they implied they are not just focusing on the onion during that time, but doing a whole lot of other prep and cooling work all at the same time.
I find that for most cooking tasks, sight and sound are more reliable indicators, and in many cases, the food will need to be stir or flipped so as not to burn.