You are right but at least they are given ahead of time so you do have time to study them.
The fun comes in after you practice a song list for a week and some smartass wants to change the key on the day of the performance of a song. The NNS makes this easy to do.
The Nashville Numbering System is something you do not see mentioned very often on the forum.
I use it and it does make memorizing a song easier, and of course when you know the chord progressions and and a singer wants the song transposed to a different key, usually because of their voice range, it is easy to do on the fly.
Take a look at the 12 Bar Blues.
It doesn’t get much easier than that. 3 Chords I IV V (typically dominant 7ths), over 12 bars (usually), in a preordained format played over and over and over. Although the second bar and turnaround can vary somewhat.
In a song with an Intro, Verse, Chorus, and Outro the chord progressions for each verse and the chorus are usually the same. But as with most things in music you can have variations, such as a key change thrown in just to keep it interesting. 
Just so we don’t get sidetracked into the NNS here I started a new topic on it.
Here is a link if you are interested. Nashville Numbering System
Please pose any questions, advice, suggestions etc regarding the NNS there.
Thank you 