If you are leaking a half gallon of oil every 2 weeks then the entire undercarriage would be totally saturated and leaving multiple puddles underneath the vehicle spanning from the rear main seal all the way back.
If you are not seeing a catastrophic mess I think most of your oil consumption is being burned in the combustion chambers, a second clue is how the consumption changes based on "how you drive it"; pushing it harder will cause greater oil consumption if you are burning the oil but wouldn't have much effect if the oil is just leaking out.
If you are not seeing a catastrophic mess I think most of your oil consumption is being burned in the combustion chambers, a second clue is how the consumption changes based on "how you drive it"; pushing it harder will cause greater oil consumption if you are burning the oil but wouldn't have much effect if the oil is just leaking out.