I did make a stir plate from a computer hard drive and some bits from Radio Shack (remember them?). The stir bar magnet would sometimes wander from its coupling and bash about in the container. There are rare reportings of loose stir bars breaking the glass (I had one go through an Erlenmeyer wall once in 35 years of lab work), alternatively, the magnet would merely wiggle against the wall, away from the center.
So I read up on oxygenating starters and wort. Here's one https://www.youtube.com/watch?v=75gpehf_6Gk
from Wyeast. Assuming that a starter benefits from introducing air (and there are those who believe that it isn't needed), I figured that being able to shake the container vigorously would be comparable to a spinning stir bar vortex that also crushes yeast at the same time. I switched to a 2 Liter plastic soda bottle for making 1 Liter starters. After carefully sanitizing the bottle, adding wort with SpG of 1.036 and yeast, I shake it initially for one full minute, then agitate some more periodically throughout the day, watching for its own little Krausen to develop. It never fails to generate pressure that needs to be relieved. One less piece of equipment to worry about. My next batch uses US 05 and will be pitched dry into cooled wort, no starter needed. I'll get a photo of the soda bottle starter after that.
If I let the starter settle and decant the supernatant, the yeast can then be pitched in more concentrated form than a slurry of starter. The number of cells that are viable (with vitality) is a guess, but it works. Lag time is always < 26 hours, except for a recent pitch of WY 1272 into SpG of 1.074 where it took 36 hours to get started. That may have been some osmotic shock at play on a recycled batch of yeast. That batch is bottled and waiting until sometime in May to be sampled.
I used an Inkbird for time and temperature tracking (not control) over 15 batches, but found that the data was very consistent from one batch to another and did not really add any value to my batch records already on paper. If I were a production facility trying to make the same beer consistently batch after batch, it would be a different story. I simply enjoy making new recipes simply more than that.
You can monitor and influence the variables to whatever degree you wish, as long as you make beer.