What The File saves lots of time, and believe me, when you have a tight timeline to deal with, your time is as precious as gold.
With What The File there is no need to investigate your theme folder and no need on spending countless time trying to understand which template file is the one needed to be edited for that particular hack you want to do or that extra function you want to add.
Once installed, the plugin's widget resides at the top right corner of your admin bar and upon visiting the live WP site tells you instantly what template page is it that you have to edit in order to see the changes there.
Easy Peasy..! 5 Stars rating as that's is the WP limit, otherwise, I would give it even more..!