I don’t know if you have ever had an IQ test, but IQ can impact how fast someone learns. A particularly brilliant person with IQ over 140 can memorize a lot of things the first time they hear it, while someone else with a still high IQ of 120 might have to study to memorize the same thing. Dropping further down the IQ range would mean even more studying is required to achieve the same memorization.
Some people also have a knack for some subjects and not others. Math might be easy to one person and grammar could be difficult. Subjects like history that require a lot of memorization of facts might be a challenge for some people. So it could be that they need much more repetition to learn something that another person could master quickly.
People also have different goals. For example, one of my daughter’s classmates in high school was aiming for Valedictorian, which she ultimately achieved. For her, it wasn’t enough to make all As. My daughter made all As and took 15 AP courses, but she was still not in the top 10 at her school. To be at the top required making very high As in the upper 90s for all courses. That girl studied a lot more than my daughter, and was much more diligent about always completing homework and turning it in on time, because she wanted to be Valedictorian. That required more effort and studying on a daily basis throughout high school for her to wind up at the top. Since the Valedictorian also plans to become a doctor, her study skills and diligence will pay off throughout college, because it takes very high grades in college in difficult science courses to get into medical school.
Because everyone has different strengths and goals, they should not be judged one way or another for how long it takes them to learn something, or for wanting to do extra studying to be SURE they have mastered the material. Some people do not want to risk a low grade (or even a B or a low A) because of their personal goals, so they might study extra just to be 100% sure they have it mastered.
The parents who are pushing for extra studying to ensure mastery probably have legitimate reasons for doing so. It could be that they know their child needs that much studying to learn. It could also be that they want to remove risk of anything less than an A because they cannot afford to send their child to college without an academic merit scholarship, or perhaps their child wants to go to a top tier university. Their child may also want to become a doctor eventually or pursue some other career requiring very high grades throughout college, and they want to instill good study habits early on.
If you look up the actual data on Asians, the “pushy Asian parents” as you put it are having tremendous success across generations. Asians make more money than other races in the USA on average because they are successfully pursuing difficult careers requiring exceptional academic achievements. Asian students dominate National Merit Finalist rankings and national science awards compared to their percentage of the population. They now make up around 20% of Ivy university students and around 40% of top California universities like Berkeley. Asians are doing something right. So what appears “pushy” to you could be the secret to long-term success.
Of course, not all Asian parents are “pushy” and not all Asians are high achieving, and plenty of parents of every race could be perceived as “pushy” whether it relates to academics or sports or performing arts. Would you view this all differently if it were a friend accomplished in sports whose parents insisted they practice their sport for an hour a day? What if the parents insisted their musically inclined child practiced playing their instrument for an hour a day? What if this family were not Asian and were some other race, would you have the same reaction?
It’s really best to just focus on yourself and what works for you and your goals, and not criticize or question what effort another person and family puts into academics.