Anecdotal, but I have worked on trail crews / outdoor jobs (including crews that were 100% women) and we all used cups for multiple months at a time with no problems. Many women in the outdoors community in the U.S. (forest service, wildland firefighting, long distance trail hikers) swear by them. 

I haven't used Asan's cup specifically, so what I'm saying could be way off base, but I'm extremely skeptical a cup would last more than 2 years, max. By "last," I mean, "the owner is willing to use it." Having used menstrual cups myself, and existing in social circles where menstrual cups are the norm, they get quite smelly after ~18-24 months of use, even with regular cleaning. It's not pleasant to then insert that product back into your body, and the smell can even foul the restroom. This is obviously anecdotal, but I'd estimate I've had ~10 people who menstruate share this sentiment with me over the years. 

There is also a steep learning curve with learning how to use a cup correctly. It's not as intuitive as it seems, and you have to be very comfortable with your body. Even once you know how, it can be frustrating. 

I'm not surprised more school days weren't gained from cups, because it assumes the reason school is missed is because of lack of period products. That contributes, but a large reason is also period PAIN and other symptoms of discomfort: in a meta-analysis of 38 studies (15 high income) encompassing 21,500 women, 20.1% missed school because of period pain, and 40.9% reported their academic performance was impacted due to pain. (Source: https://journals.sagepub.com/doi/abs/10.1089/jwh.2018.7615?cf-mal-redirected=true&)

I love menstrual cups and think they solve many problems and should absolutely be an OPTION for women. But they are never going to be the only correct choice.