I take around 40mg once a day. I get everything in one package deal for 8 hours, mood lift, focus enhancement, and the works. I already have a high stim tolerance (and keep in mind that tolerance rise just means *I'm not getting high anymore*, as ADHD is linked with D4 receptors that don't downregulate). The only issue is the comedown, which sucks; but, it is what it is.20mg 2x a day is more than you think if you have very clean product. Desoxyn has a max daily limit of 25mg. And if you are truly using it for therapeutic use, then trying to potentiate it with other medications would be not be advisable. Not to be rude, but your it seems like you are bouncing back and forth between wanting to use it for medical purposes and recreational purposes.
I don't see the purpose of being stimulated for 16h by twice a day dosing... That's quite torturous.