“Surely would have peaked quickly in severe Covid folks.”

The clinical situation may dictate quicker in some cases. If the patient is in the ICU on a ventilator you need to put out the fire quickly. RO doesn’t happen in minutes, my memory is ramp up over a couple days. The equivalent would be a TBI patient with status epilepticus who needs a continuous IV pentobarbital infusion…rapid drug distribution through the most available route (IV) gets the job done.