The most I've taken is 80mg of Xanax in a day. Valium I've taken over 1000mg in a day, Klonopin I think around 60mg in a day and Ativan around 80mg in a day, I believe.
While I certainly do NOT recommend such dosages, benzos are indeed remarkably non-toxic. This is what originally made them so wildly popular with doctors.
If you take 30 Seconal (especially with alcohol) you are DEAD. A Seconal OD killed Judy Garland. Nembutal is another highly toxic barb, which killed Marilyn Monroe. Though back when I was born any neurotic housewife could visit her caring physician and readily get a script for a bottle of #100 Seconal or Nembutal.
Want a very common example of a highly toxic drug found in most homes: alcohol, which is fatal at only 10 times the normal dosage. Notably more toxic than quite a few of the drugs that the DEA has decided should be entirely illegal.
Know what the standard ER treatment is for a "benzo OD"? They put you on a bed & let you sleep it off, sending you home with a few thousand dollar motel bill, for the world's most expensive nap. Despite my sarcasm, that is exactly what they do. There is a drug that will reverse the effects of a benzo OD, though it will almost surely produce seizures, making sleeping it off by far the best & safest treatment. A treatment that effectively is no treatment at all, unless you lack a bed at home (or park bench if homeless).
I knew a woman, who used to be on SAS who "Oded" on Ativan -- about 50 mg. She ended up in the hospital against her will, fully awake to "enjoy" the experience till she finally fell asleep some 8 hours later. Do you really need emergency medical treatment for a dosage that doesn't even produce a nap?
Being broke, I presume tax-payers in the state of IL paid for that adventure. I still regular text with her (as she is too afraid to use voice). Ironic, given that we were notably more intimate than mere chatting when I met her in person years ago. She would be one of the naughty young ladies on SAS who I whipped to tears, but what else would you expect from a self-described sadist.