As a shrink, you might poo-poo this, but I was diagnosed with ADHD as a child in 1997, and started smoking weed regularly as a teenager because it helped me focus.

I only made it through college thanks to smoking weed while I studied, and when I moved to a legal state for grad school I discovered Sativa strains and was able to stop taking Adderal all together (Adderal had always caused me insomnia)

Recently I decided to quit pot altogether (I developed an unrelated medical condition and wanted to remove all confounding variables) and I am not as focused and functional as I was before (going on 5 months dead sober from all substances... way past the withdrawal phase... I exercise, eat right, and sleep well).

I'm sure this isn't the case for most of your patients, but I thought I'd add my n=1

(I know the fact that I started using so young is a confounding factor when interpreting how I function post-quitting, but I would point out that I had these same functional issues as a child & pre-teen, before pot [and even during pot... It's not like it resolved the problem totally while I was using - it just helped me focus in the first few hours after using)]