You need to keep your lint screen/filter in the dryer clean. My wife cleans ours after every use. The vent pipe to the outside and the flapper need to be cleaned periodically as well, since no lint screen stops it all.
The idea is to dry the clothes with warm dry air flowing through them to the outside; not par boiling them with hot air and trapped moisture.
Most dryers today have a moisture sensor in the drum that controls how long the unit runs. If you trap/****** the moisture escaping through a clogged filter/vent system you cause the dryer to run longer, resulting in wasted electricity and extra damage/wear to the clothes.
Some say that fabric dryer sheets coat the sensor, others say the liquid softner does.
The advantage of the sheets is that they remove static electricity as well as soften.
We have used them in the same dryer for over 20 years without any problems to the sensor.
You have to follow the directions and keep the lint filter clean so there is good air flow.