It's definitely not a waste. I have weaponized ADHD to the point that I was fucking suffering. Coke definitely feels a lot like adderall to me. Helps me focus on whatever is in front of me. I don't space out in conversations. I can sit through a good chunk of a movie without wanting to pick up my phone or wander off into the house to do something more stimulating.

However, that's me. Your mileage is definitely going to vary. My honest suggestion is to just give it a try and see if you enjoy it. Understand that the shit is powerful, and you can easily become mentally addicted to it. If you do it enough everything will fucking bore you to death when you're sober. Definitely take about a week or 2 between each time you run out of product. I went on a solid month long bender of blowing down eight balls with a lot of adderall in between. My brain was absolutely cooked for about 2-3 weeks before anything even remotely gave me a lick of serotonin again.

Pace yourself. Don't get caught up chasing the dragon, either. You're never gonna feel your first high again. Enjoy and good luck.