Like others, i prefer separate projects for each song, but i do it differently. Here is why...
If you create all the projects at the start, you have to do lots of work again and again.
I create a project for the first song alone. Mix it... Then make a copy of that project, delete audio. Save and close the project. Go to the audio folder for the new project and delete all audio.
Next, in the long project made during the gig, set markers around the next song, split, bounce to clips, copy and paste into new project.
Now the new project has all the fx and fader pan, sends etc set up while mixing the last song.
If i do this for all the songs and when i finish go back and do the first two tracks again, the result is a fairly consistent mix.
This is an old video now, but it shows some of what i describe above.
If you end up working in one giant project, the navigator view can be handy. You can also save a snapshot per song making it easier to get back to compressor and limiter settings used to bounce each song.