If the heat mat is large enough yes, although there is always a small temperature gradient!

My dart frog tank varies from 25c at the hot end to 22c at the other.

For my Malayan horned frogs, that require a constant of about 25c I've had to mount 2x30w heatmats on one side of the tank completely covering it!

There is a lot of trial and error involved!

Thanks for the extra reputation point!