This is a great opportunity because it reflects a basic need of worldbuilding
And what is that need? You need to choose what rule you want.
As you can imagine, there is no science, no real-world example, nothing that we can draw from that will give you an objective and definitive answer. Insofar as we know, precognition doesn't exist. That puts you square in the middle of "the result will be what you want it to be."
I know that's not what you wanted to hear, but it's actually a good place to be! Here there be dragons worldbuilding! And you get to decide what the rules of your imaginary world are and how those rules work.
However, we can give you some pointers
Let's ask ourselves what about real life might contribute to this issue?
People "think" at different speeds. This is actually a lot more complicated than it sounds. Some people are naturally more observant than others. Some people can reach a conclusion faster than others. Some people have better control during a fight (see adrenaline and the fight/flight reflex) than others. Some people are better trained than others. What all this means is that you will believably never have a situation where the two opponents are perfectly matched. When all the pros and cons are analyzed, one will always have an advantage over the other. Unfortunately, this is more storybuilding than it is worldbuilding.
Then there's bad luck. Or good luck! It depends on whether or not you're the winner. I've watched tennis matches played by opponents so well balanced that it wasn't someone's game to win... it was someone's game to lose. That's a very real thing. It reflects the reality that in some cases, it's not the first to outsmart their opponent who wins, but the first who makes a mistake who loses. And that ignores the simple truth that someti... SQUIRREL! Yup, sometimes you just have the bad luck of the exact type of pretty girl walking by at exactly the wrong time to get that specific "you're sleepin' on the couch tonight, mister" look from your wife. Crap happens.
How much of an advantage precognition is depends heavily on the rules of its operation. Is the practitioner actually seeing something in their mind? That's a huge distraction. Is it intuitive, meaning it's a better form of what a good fighter can do anyway through training ("guessing" or predicting what will happen next)? This is an important question because how you define precognition determines whether two gods are fighting or two people struggling to use a tool. Think of it this way... in a world where pretty much every soldier has an M1 carbine the rare soldier lugging around an M50 machine gun has a distinct advantage... kinda... because that machine gun has negatives that are very useful to a story (it's heavy, it has greater recoil, it takes time to set up, if simply held and fired it gets HOT...). BTW, godlike characters are boring. You want weaknesses or your readers won't relate well to the story.
In other words, you're asking us the wrong question
Yup, there is no right answer to your question and that's an important learning experience for asking future questions. Note from the Help Center that giving us your answers and expecting more (telling us what you've already considered) is prohibited unless you're explaining why they're not valuable answers, in which case they become conditions. Note also that questions are expected to identify a problem to be solved. I know you feel that's what you identified, but I hope I've helped you understand that you've asked us to voice opinions with no hope of evidence that one opinion is better than another (also prohibited...). It's worth taking the time to read the fist two pages in the Help Center (it's useful to read them all, but those are the most important).
For future reference, our sweet spot is answering questions like, "I want X in my world, how do I rationalize it?" and "I want X in my world but need help working out the rules, my specific problem today is X...." In other words, you've already made your choice about what you want in your world and need help smoothing out the rules. We're great at that. Helping you decide which way to go? You'd be surprised how hard that is — if it can be done at all.
Cheers and happy worldbuilding!