Funny, I always interpreted the gray branches in that diagram to mean short lived branches.

I just have dev and master with all my projects. Everything else is short lived. And short lived branches are rebased and squashed. Also, all devs work with forks to keep upstream pristine.

And there are those dogmatic about trunk development. I think if you follow the rule of thumb of don’t let dev and master get too out of sync you don’t need to do trunk.