Answer:
In general , While estimating a bodies temperature that temperature is not the same for long, the temperature of the body is not at homeostasis, the temperature constantly has bumps and drops in the temperature this causes in accuracy thats why the thermometer takes 10-20 seconds because it takes the average of all the temperature's so it is accurate, that is a difficulty when estimating temperature because estimates are not good and the temperature keeps having ups and downs.
