DIAGNOSIS Inadequate drying is almost never the dryer's 'heating' part failing first. It's almost always an airflow problem. The hot air can't get through the wet clothes and out the vent, so it just sits there, gets saturated, and quits working.
FIX 1. Clean the lint filter—really clean it, under running water, because fabric softener sheets leave a film. 2. Check the exhaust vent path. Pull the dryer out, disconnect the duct, and check for a lint plug at the dryer outlet. Then check the house vent all the way outside. A bird's nest or severe clog here is common. 3. Make sure you're not overloading the drum. Clothes need room to tumble for the hot air to circulate.
IF THAT DIDN'T WORK If airflow is perfect, then you can suspect the heating element or thermal fuses. But on this Samsung model, a restricted airflow will usually trigger a "tE" or "dE" error before the element fails outright.
HEADS UP Running the dryer with a clogged vent is incredibly inefficient and a major fire risk. It's also hard on the dryer's heater and motor, leading to premature failure. Treat long dry times as a maintenance alert.