Should I use a separate controller with my aquarium heater?

Specialist-community threads on r/Aquariums repeatedly recommend pairing any submersible heater with an external controller (often an Inkbird-style thermostat) because internal thermostats are the most common failure point. A controller cuts power if the heater sticks on, and lets you verify temperature against a second sensor. It's the single most consistent piece of advice across high-trust hobbyist sources.