Honestly I've never oxygenated a mead. You don't boil it, so there's oxygen in it already (unlike boiling 5 gallons of beer which drives off every O2 molecule).
I would only oxygenate prior to pitching and then do a staggered nutrient addition. but that's just me. I don't see a need to keep adding O2. Others will disagree but all my great meads will argue its not necessary
Primary: English Mild
On tap: Pale Ale, Lancelot's Wheat, English Brown Ale, Steam Beer, HoovNuts IPA
Bottled: MOAM, Braggot, Raspberry Melomel, Merlot, Apfelwein, Pyment, Sweet mead, Cabernet
Gal in 2009: 27, Gal in 2010: 34, Gal in 2011: 13, Gal in 2012: 10