Circumstances dictate evenings for me and often starting after 7 even. Drennan isotopes allow me to fish in winter and they work into dark alright now too, if I decide to hang on a bit longer. But even 2 hours, or less sometimes is a good remedy for a testing day.
Starting before dawn and full of hope is a great way to start the day in expectation of good things. Trouble is I can't get to sleep for worrying about the fish I missed, or the change of method I need to apply tomorrow. Then fail to get up of course. I am always keen to do at least one full dusk to dawn session each year but that is far from my typical excursion.