2004 Chevy Cavalier thermostat

Engine Cooling problem
2004 Chevy Cavalier 4 cyl Front Wheel Drive Automatic

I was reading on your website that a thermostat should last quite a while. I have a 2004 chev cavalier and have already change 4 of them in five years because they stop functioning properly. In the extreme cold especially it takes an hout for the temp gauge to get to 90 degrees. When it finallly gets there it will come back down if I leave the car idiling and the heater air will get warm instead of hot like it usually does. Is the only way to see if a thermostat is working properly on these cars, is to check it on the computer to see if it is ruinning at optimun temp.