Yep, what Aaron said.
Just answering the question from my own experience.
I got caught up in the "must service every 5,000kms" for the first 2 years of ownership and used synthetic oils.
Cost me a fortune as I was doing 800kms every week, so I decided to see how the car was with 7500km service intervals.
Was all good, so went to 10,000km intervals and again, ran beautifully.
lol, it is probably not necessary to change every 5,000kms... just as it is probably not necessary to use Group V oil (Motul 300v, Redline, NEO).
I like to use the best fluids/oils and service less frequently, Aaron likes to use damn good oil and change every 5,000, Craig does his every 10-12,000, other like to have Nissan service their cars.
It's your car, so do whatever you are most comfortable with.