Auto dry is one of the features I really like on my tumble dryer, it's the sort that uses an extra thermistor to try to determine moisture content, I rarely use it on timed dry, only when there's not enough time to fully dry the wash before the end of the cheap rate economy 7 electricity period, when the electric rates switch back to full price.
It's not perfectly accurate, some of the items will often need to go back on when I use "cupboard dry" (the driest setting), like clothing with thick cuffs, but that usually doesn't take much more than an extra 10 - 20 minutes or so. On "delicates" it turns the element on and off to reduce the temperature, and it can sometimes end up extending the drying time by as much as an extra hour, but when I tested it with a power monitor, because it runs with the element off so much, it appears to use a fair bit less electricity than full heat with a similar load.
The dryer is about 18-19 years old and the electronics have been fine. Electronics can be made reliable if the manufacturer wants, and doesn't overly cheap out on the design or components. The mechanical timer on the previous dryer I used burnt up about that age, although that was purely an assembly issue, they'd managed to miss one of the spade terminals when connecting up the wires, and wedge a female spade connector tightly down the side of the terminal, and it took over 20 years to work loose. And I was able to easily repair it, by cutting all the melted plastic away, including the burnt carbonised plastic corner off the timer, and melting some plastic around the timer terminal that had melted out of position, to remount it and the internal contact where it belonged.
