Some of the most famous words ever from Mark Twain (Samuel Langhorne Clemens) are "Eat a live frog first thing in the morning and nothing worse will happen to you the rest of the day." We usually interpret the quote to mean that we should get off our duffs and tackle what's big, challenging, or scary for us right away. After that, it's easy peasy, and life is better because we don't have the anxiety of the pending job darkening everything else we do.
But not everybody works this way.
For some people, there's benefit to letting the frog simmer in the pot until dinnertime. The idea here follows the psychological principle that, if you build up many small successes over time, then you'll gain the confidence you need to tackle something bigger and finish strong.
Leaders often cite this concept when they give advice to people wanting to break into something new, climb the ladder, or make new connections. It's also a favorite of educators or counselors who want to encourage students or address behavioral concerns. It connects to the wider, science-backed concepts that exposure to positive words and experiences can give a better color to whatever comes after them and wire the brain to look for more good.
If you're one of these people, then eating the frog might not help you--it might crush you. You might spend the entire big task worrying that something is going to go wrong or doubting yourself. So even if it goes well, by the end, you're mentally (and maybe even physically) exhausted from the stress. You might even be in a sourer mood than when you started, because you can't get over the "unfairness" of having been thrown into the deep end right away.
And now you've still got the rest of your entire agenda to handle as you try to come out of fight-or-flight mode.
Good luck with that.
The bottom line is, eating the frog probably isn't one-size-fits-all. If you already have pretty good confidence, then you might be able to jump right in and knock out the toughest things on your list before the sun is barely up.
But if you're not there yet, it might benefit you to give yourself a few wins first. And, importantly, there's zero shame in being at this point. You'll grow, and even little kids who graze for hours before they learn to chow in one sitting still end up eating their meal (and asking for dessert to boot).
All that really matters in the end is that your plate is clean.