You can't read aresti like that because sooner or later you'll walk into trouble.
You have to recognize at some point that sometimes the figures are printed in
a way that will make it easier to put them on the piece of paper.

What you have to do is read the aresti, recognize the figure and read
the F&JG and see how it needs to be flown in a sequence.

In this case the hammerhead shows the exit point midway the upline but that doesn't mean anything.
You can fly it like that and there will be no deduction for it but you don't have to.
Take a look at the sportsman sequence figure #2. Almost the same figure but there is a roll
on the downline. How do I know it's on the downline and not the upline? And even though
it looks like it's on the bottom of the downline it still needs to be centered.

To answer your question, I would exit the hammerhead around the same level as the entry.
Only because the figure overall will look better and I will be better setup for the next figure.

I hope I'm not confusing you more

Stratos.-