Thermal fuses burn out to prevent fires. All dryers have a high limit safety thermostat that cuts power to the element at a lower temperature than the thermal fuse burnout temperature. In addition, the dryer may have a thermometer and temperature control or a simple thermostat. So there are three temperature sensors in most dryers, and the thermal fuse is the last.
The leading cause of thermal fuse burnout is obstructed airflow. Check the exhaust path for excessive lint or debris all the way to the exit point of the exhaust pipe. Check the blower wheel to make sure it isn't broken or clogged up. This can be done by using "cool down" or "air fluff" mode. If the unit has a lint trap on the outside of the drum, make sure it seals up when installed.
If there is good airflow and the heater is working correctly, the thermal fuse should not burn out. If the temperature controls are not doing their jobs, replace them.