When measuring specific heat, why should your final temperature be the maximum temperature reached calorimeter?

Answer 1

Joules in = spec heat * m * delta T
so
specific heat = joules/ ( m delta T)

The more accurate delta T, the more accurate the resulting specific heat
if you are off one degree in ten
you have a 10 % error
if you are off one degree in 100, you have a 1 % error