Whilst it is an unattainable goal to strive for, Perfection kinda has to be on the mind of most top players in any competitive game/profession. However, the step-wise process towards this is best described by Self-Improvement. ... that probably sounds confusing as all get-out, so lemme try to clarify. (SPOILER: I'm not the best person at articulating my thoughts, so this will probably be confusing still :/)
From my personal experience, people have a tendency to become complacent very quickly when they feel like they have achieved all that they can in a given situation. Whether it be finishing your homework a week early and never looking at it again, climbing to the top of the corporate ladder at your job, or even being in a seemingly defeat-less position in Pokémon, people very quickly switch off when they think they've "done it all".
Take exams for example. In the Uni I did my Undergrad at, you were free to hand in your paper and walk out of an exam once half an hour had passed (unless it was the last 15 minutes but details). Lots of people in my classes finished like an hour early and immediately handed the paper over and left, feeling super-confident with how they had done. But when the results came back they were much worse than expected. Why? Well, rushing answers aside they didn't bother to check through what they had done for errors. They had so much time left, but they felt like they had already done everything right so they got complacent. Meanwhile, those who stayed the full time and check/redid stuff they found to be wrong in their answers scored way better, despite not inherently being better at the subject. Sounds obvious when you put it that way, but you'd be surprised at how many people fall into this trap.
The same happens for improvement in a gaming scenario. The most logical way to strive for Self-Improvement is to set short-term goals. "I'll learn about EV's this week, IV's the next". This is excellent... up to a point. That point will be different for everyone, but there WILL come a time where you think you've done everything you can to improve yourself, and/or the next thing on your list is so hard that you put it off indefinitely. What usually happens there is that you get complacent. This often manifests itself in blaming factors that are seemingly outside of your control (usually hax - god knows I've done that one myself often enough). After all, there's no way that YOU can improve now, right? You've already done everything! Of course, you haven't, but now you're stuck in this mental trap... and it's often hard to realise you're even in it to begin with.
This is where the whole Perfection thing comes in. Perfection is of course unattainable, but most people realise this before even starting. However, it serves as an indefinite long-term goal to shoot for, to prevent complacency. Those who are at the top of their profession are always looking for new ways to improve because they are hoping to one day reach that perfection goal. If they find themselves in a losing position, the first thought usually isn't "Oh if that flinch didn't happen I'd have won this", it's "How could I have done this better to account for the chance of flinching". This is super-oversimplified but I hope it gets the point across. Keeping a long-term goal like this in mind is the key to giving your short-term goals context, allowing for constant self-analysis, and therefore self-improvement. It all loops around!
You see this a lot from players like Aaron Zheng in his Road to Ranked videos. He's clearly very good and knowledgeable, but he's also constantly pointing out his flaws and what he could've done better each turn. Despite being a top competitor already, he knows he isn't perfect, so he sets his sights to even higher levels.
tl;dr - Perfection needs to be the long-term goal of Self-Improvement, else people get too comfy in their ways and can never change for the better.
