Restricted vent airflow
The most common cause of slow drying is a clogged vent line. Lint collects in the duct and the dryer can't exhaust moist air.
Why lint is dangerous
Lint is very flammable. When airflow is blocked, the dryer runs hotter and the risk of a fire grows.
Heating problems
If the dryer tumbles with no heat at all, the heating element, thermal fuse or gas igniter may have failed.
Easy habits that help
Clean the lint screen every load, avoid crushed foil ducts, and don't overload the drum.
When to call a pro
If drying still takes two cycles, or you notice a burning smell, stop using the dryer and book a repair.