do responsive heat detectors do what they are supposed to?

Answer 1

they are responsive if that's what you mean.

Answer 2

It depends on what you want them to do. People often do not set goals when they buy fire protection devices, or their goals are fuzzy.

I suspect that your goal is not to detect heat, but to detect heat for a reason. Most likely that reason is for life safety.

If you want to detect heat for any purpose, you want to be sure that the heat is detected before whatever makes the heat does any damage. For example, in a fire smoke can incapacitate building occupants even before a heat detector can operate.

Heat detectors make a substantial contribution to life safety, but there are better tools. Smoke detectors for one.

Regardless of whether one chooses battery-operated or AC powered smoke detectors, the photoelectric-type are far superior to ionization types for residential use.