Hello and welcome..
Wow, that's an incredible amount of xanax you're taking. But if you need it you need it.
Ideally the doses should be taken 8am and 8pm. If you take it at 4pm then wait until 9am the next day, that's way too long.
I have no idea why there would be that limit on Xanax in the first place. That would be the first thing to learn, what is it toxic to? For example, you can't take too many Tylenol in a day because it's liver toxic. So what is Xanax toxic to? The main problem with taking it the way you're taking it is it's addictive taken that way, and as with all addictive drugs, eventually you keep increasing the dose just to run in place. It also stays in the body a very short amount of time, so it stops working way before you're taking your next dose, at least biologically -- the brain can get used to feeling good in ways other than just having meds in your system. So if it's a toxicity problem, you might be considering other options for your treatment, although stopping this med will be long and difficult at this point. I'd call my pharmacist, toxicity is one of the few things they actually study, or my psychiatrist and find out what the danger is. That will answer your question about how stringent this advice is or whether it's just there to prevent abuse of an addictive drug.