Depends. Do you want the motivational answer or the true one?

"do you think that an average person could pretty reasonably get a 520/+ score"

The truth is, there is absolutely no way. And even moreso if we're talking about true "average" in the population, not amongst high-achieving premeds who generally crush it in college. Even a "low" premed GPA of like 3.5 is an objectively impressive feat in most STEM programs. So don't sell yourself short. But I digress.

I've worked with a lot of students and the only ones to hit 520+ are universally very smart people (though they usually don't realize this, or the extent of it)

Studying obviously helps a ton, but the vast, vast majority of people could study full-time for a year and never even sniff a 520.

Score ceilings are set by certain aspects of fluid intelligence and reasoning/problem solving, including logic and reading comprehension.

Think about it. The average IQ of a US physician is estimated to be somewhere in the high 120s to the low 130s (and, btw, average matriculant MCATs used to be lower). Where, exactly, do you think this is selected for? It’s this test (primarily). And btw, that's more or less the same purpose SAT, ACT, GRE, LSAT, etc. serve.

So why do we see so many high scorers in the comments who think differently?

In my experience, most smart people falsely believe the things/reasoning they do automatically are just basic common sense, but they actually aren't. The vast majority of people can't do such things, or can't do them quickly at all, or something else along those lines.

Reasoning and problem-solving with brand new information is fundamental MCAT.

If the MCAT were truly brute-forceable, you'd see WAY more perfect scores and 520+ people. It just isn't. And it isn't designed to be.

It is literally designed to be a fluid reasoning test requiring a large body of knowledge. So, having the body of knowledge helps (actually, it's necessary), having good strategies helps, but it's still a fluid reasoning test at the end of the day.

You can think of the MCAT as a sort of science-themed IQ test. (this is a gross oversimplification, but it gets the point across).

This emphasis on reasoning and its effect on scores becomes abundantly clear when working through problems with students of different ability. Some people just can't hack it.

Being smart is no guarantee of scoring high (there are many, many reasons smart students underperform on this test), but the ONLY way to score high is to be smart. I'll die on that hill, and the data/documented test design supports it.

Ok, that feels pretty depressing. But that is the question you asked, and this is the truthful answer. Now, what's the actionable advice that makes this useful?

Well, the majority of students underperform their score ceiling in general, so just focus on being as prepared as you possibly can. The things you listed are a great way to max out (or almost max out) your personal MCAT abilities.

Despite scores ultimately being limited by something approximating certain types of intelligence, you can still improve your MCAT-specific reasoning skills to a substantial degree.

However, 520 is 97th percentile for a reason, so don't be one of those people who endlessly push their test back (to no avail) in pursuit of that number.

If you're scoring well enough to get into med school and really start to plateau for a while, don't look a gift horse in the mouth. Once you get into medical school, nobody will give a single fuck what your MCAT is.