My Yeti is 3 years old in March, has now done 56k miles and has been on variable or "on-demand" servicing in that time. Three services performed at roughly 18k, 35k and 54k.
A lot depends on your mileage and useage. Mine does nearly 100 miles a day commuting across Wales to Ludlow, on typical Welsh cross-country A roads, so gets nice and hot.