I've made a resolution to stop writing new lyrics and finish up old ones instead. AND... instead of writing new songs, I'll finish up and improve old ones.
So, on a good week, I only spend about an average of one to two hours on new lyrics, and maybe three hours on old ones.
In a bad week, I write two new ones.
The good part about trying to NOT write lyrics is that you don't waste a lot of time on substandard concepts.
The bad part is that you lose a lot of ideas that might go somewhere, or contribute something to another song if written down.