This is something about which I've been thinking recently. My feeling is that the oral route has an extended duration because there's a larger amount simply 'hanging around' in one's system due to the higher dose requirement. Sublingual is absorbed more directly and bypasses the gastrointestinal metabolism hence the (substantially) lower dose requirement.
And I hoped I've achieved a suitable balance of simplicity and actually making sense here!
“There is a way of manipulating matter and energy so as to produce what modern scientists call 'a field of force'. The field acts on the observer and puts him in a privileged position vis-à-vis the universe. From this position he has access to the realities which are ordinarily hidden from us by time and space, matter and energy. This is what we call the Great Work."
― Jacques Bergier, quoting Fulcanelli