Do you use thermal sensors in your pc case?

My motherboard has 3 thermal sensors.

However, with all of the built-in temperature monitoring that my motherboard has, I don't see a good place to put them.

Currently, I have them monitoring the temp of the air as it enters the computer case, the temp of the air in the middle of the computer case, and as it exits.

This temp is the lowest of all of the temps that are monitored and only varies by 1 degree. Incoming air is 21 Celsius and outgoing is 22 Celsius.

When I ran sensors, I stuck one in the heat sink on the cpu, just up in there (carefully).
Another in the main gpu heat sink the third I put on the power supply.
That was with a fan controller with a temp display. With everything running perfectly, I just noted the temps and if anything ever went up I'd check it out.