I don't.

My most-productive compost operation mostly just consisted of just piling stuff up beside my brick shed, which was conveniently near an outside door on my kitchen.

The rest of the process consisted of giving it a bit of a toss with a hoe, a shovel, or a fork if I was outside, bored, and felt like doing that, or giving it a bit of water from the garden hose if it had been very hot and dry. And I did as little of this as possible because taking care of compost, while certainly interesting to me, is just not something I generally enjoy doing.

I really didn't pay much attention to it.

By the time spring came 'round again and I had a use for the stuff, I had plenty of it for the garden.

And this worked very well -- for me, on my scale, in my region, with my needs.

Therefore, I do not need to monitor my compost.

---

But not all composting operations are lazy. Sometimes, they are very active. And some operations are large enough (or the available space small enough) that real estate becomes a seriously-limiting factor.

And in these instances, optimizing the process to get higher-quality compost faster can become a very desirable goal.

Optimization of composting is not dissimilar to optimization of any other process, wherein: Having some good data is better than having no data.