Folks, I predict we are about to see much more interest in the QBL/MCL connection. The MCL subsidiar, page-6

Speaking as a pharmacist, if you consider the current treatments for more severe pain being primarily Oxycodone, the slow and fast release formulations are commonly prescribed simultaneously to the one patient.
This is very likely to be the treatment regimen if/when CBD takes over from Opioids.
So it is never the case of which is better; slow, or fast release. Both are extremely important.