From what I've gathered over the years, dextro-amp is primarily responsible for focus, attention, and (potentially) euphoria while levo-amp is primarily responsible for peripheral effects like anxiety, jitters, and other "body-centric" things.

As a result, I've always understood d-amp to be considered more abusable and part of the reason for the mix in Adderall and generic equivalents (although it's also allegedly a better mix for treating most ADD/ADHD).

It's why you can get Adderall if you're diagnosed with these disorders but it's rare to see anyone prescribe Dexedrine (which is just d-amp). Abuse potential is higher and also l-amp lasts longer so the mix may be seen as more effective overall as a pill you take once or maybe twice a day.

Never heard of Evekeo though.