Big load issues on AutoDry dryers
They rely heavily on everything being accessible to all the air.
If everything can heat up continuously, no cold spots or such, the triggering of the thermal setpoints will happen at a correct point of time.
AutoDry is more of an adaptive drying system then a true sensor system.
Keep in mind it's just the timer running like a timer - just with interruptions.
The time you set is basically "How long do these need to run at a certain temperature".
On the small end of the load size range, the 5kW of heating can bake moisture out of your load really quickly.
The time the timer needs to run from normal dry to cool down would equate to much more evaporation possibility then on larger loads.
On the large side of loads, even after being heated up to temp, there is still a lot of evaporation to do compared to a very small load.
But the timer is already running.
Further to this, on large loads, it can happen that at a certain point some areas get less airflow then others.
So damp patches can't drag down the temp enough to get long enough pauses of timer progression to be dried.
Same with thick items: The surface drys quickly, thus AutoDry advances quickly, but moisture can't get from the inner parts to the outer parts fast enough.
AutoDry basically does educated guessing based on how much drying you think a load needs and certain setpoints it knows to interpret.
Best example: Some very early AutoDry systems just set a cutoff point at a very high temperature. Basically assuming that once it got that hot things had to be dry (or have already burnt to dust).
Sensor drying like we used to have it over here and now only have it in 1 case was a very on point system.
The theory is that electricity travels the path of least resistance.
So no matter where a damp patch is in the laundry, if the current has to travel all the way through, it will always show a reading there is still moisture.
Very good dryers used to very dynamicly adjust target temps based on these readings dropping heat output very low towards the end of certain cycles.
Mieles Novotronic and Txxxx series dryers were amazing at it.
Cost cutting or like in the case of US dryers just plain construction criteria made a big change to sensor drying systems.
Over here they used to consist of 2 carbon brushes running along 2 bands on the outside of the drum. One was connected to the drum, one to the drum paddles. The current path was from the paddles to the drum and since dry cotton has an insane resistance, that would sense even deeper moisture pockets.
Now the path is just between these 2 strips and since the distance is very small, it can very easily happen that moisture is just missed.
Add to that that dryness targets have been moved down due to energy labelling and unsatisfactory results are common.
I don't think that either technology is inherently better if either is done right.
A good sensor system will be much more accurate even fringe situations while in most laundry tasks auto systems will do just as well if not better and usually a lot simpler and cheaper.
Some manufacturers claim to use a combination of both but yet have to see proof of that.