Now, this seems like old wine in a new flask to me. This is not the first time I've seen advice regarding doing the biggest or the most important or the least desirable job first thing in the morning while you've got energy and impulse control, both of which peter out over the course of the day. Though I've also on at least one occasion read a suggestion to do two or three small things so the adrenaline rush of completing them encourages you to take on more.
But Eat the Frog is a metaphor. You're comparing a job you're not enthused about doing to eating a frog, another thing most of wouldn't look forward to. I believe metaphors help us. They can be like mantras. I, for instance, use "staying on task" or "on task" for actual work and for craft. I need to stay on task with a humor piece, with an essay, even a piece of fiction, to keep myself from drifting off topic or theme or losing a character's voice. "Staying on task" comes from back in the day when I was harassing young kids to do any number of things. It is a metaphor I lean on.
One could argue that everyone needs a metaphor. If eating a frog helps you with your workload, embrace it.