As mentioned during the lab, the reason for taking multiple measurements of everything is so you can always calculate a precision error. For the thermocouple, it actually outputs a standard deviation for you already at each data point (this is one of the columns in the text file), however for the thermometer, you would need multiple measurements to get an average and standard deviation. The overarching theme of this course is that you absolutely always want to take repeated readings for any measured quantity in all the labs.