i don't trust that. doctors have historically completely underestimated the severity of my phobia; the last prescription i got, i couldn't even feel any effects of any drug over my sheer panic
Look at the half life of the molecule, take the low dose so that it kicks in early enough for you to take another one before needle time were it not enough. You want to still have time for the second one to kick in while making sure the first one has when deciding.