[nuancebydefault]

What do you mean by "reliable" wrt mechanical timers? I'm pretty sure the clothing dryer is a harsh environment for such a component (moisture and heat can easily cause corrosion and mechanical stress). Also, I guess timing gets less accurate over time. If there are rubbers preventing moisture from entering and oil from leaving, those rubbers will wear out.

[Fatnino]

Like another commenter said, the timer is segregated from the harsh dryer environment.

But also, some slop in the timing accuracy is just fine. The user doesn't really know how long precisely the drier needs to run to dry their clothes. They just know that if they set this timer to 45 then the clothes come out dry.

[purpleflame1257]

The timer for the dryer is typically located outside of the dryer drum itself. It is not an actuating component.

[beezlewax]

I have one that is like 40 years old. The heating element is similar to those in an oven.

The only things that broke are plastic door hinges.