2006 NC owner here with a reasonably new battery. I keep it parked in an attached garage, so no extreme cold or heat. Mine will always start after leaving it for 1 month. I probably left it for 2 months at some point in the last two years, and it started, but that feels like pushing it.
The next time a mechanic tells you cars can't sit for a few days without a battery drain problem, ask how people who park at the airport get home after a two-week trip.
my battery is in fairly good shape. when my nc was sitting for long periods (months), the old battery eventually gave out. I had to have it jumped once, then bought a li-on battery to jump it with just in case.
the real key to long storage (beyond a trickle charger) is clean gas.
right now, though, it only has to handle 2 weeks of sitting at most (in an attached garage).
The next time a mechanic tells you cars can't sit for a few days without a battery drain problem, ask how people who park at the airport get home after a two-week trip.