I'm pretty average all around, except for an excellent memory, great verbal skills, and a machine-like, inhuman work ethic when I care (obsess) about something. Even those are mostly the result of years of practice rather than natural talent, and a healthy dose of the 'tism.
I didn't need to take any remedial writing or reading classes in college, the ones I did I always did essays the night before it was due and got 95/100. Chalk that up to reading and writing for fun most of my life.
My mistake with math was memorizing the book and doing everything by rote. I tested into middle school algebra and just chinked my way through everything - 3 hours of practice problems and 3 hours of copying the book a night - up until trig/precalc, where I needed to actually think for a change. I got a C the first time, retook it and got an A. Trig identities was torture until it finally clicked.
I'm sure I could have passed calculus by retaking it with different teachers, but I was running short on time and money so I gave up. Same with discrete math. I didn't have the 12 hours a day it would take to brute force my way through the practice problems and rote-copy-memorize the book.
I need a lot of time to think to understand a subject. Taking accelerated summer courses in networking and relational database management systems was a mistake. Failed both, but the professor was excellent and gave me incompletes instead. Retook them later and got Bs.
Other than that I did fine in college until I burned out and became cynical at the scuminess of it.
I tried taking 200 level Chemistry and Anatomy/Physiology, but it was too much for even me to memorize so I dropped them. If I was 15 IQ points smarter I could've done it easily, but my dad had to marry a dummy.