I have an Ibanez Artist 2609 from 1976, it didn't need a setup then and it still doesn't need a setup now. It plays like butter, if that's the right expression, and that's said after comparing it to my more recent acquisitions which include Taylors, Martins and Santa Cruz.

Admittedly the guitar was stocked with .010's for most of it's life but now uses .012 gauge. Perhaps a refret is due sooner or later and with that probably a new setup may become necessary. But by then I'll probably be playing the harp.

Ludwig

I agree with most folks that after the initial setup only occasional tweaking is necessary due to normal wear, assuming stable heat and humidity. But I learned the hard way that you need to adjust the truss rod occasionally (annually?) even if it doesn't need it.
I had a 90's D35 that was so stable I didn't even adjust the TR for 10 years. I'd check it and it was right at .008/.010 every time so I never touched it. After all that time I decided to make a small adjustment and found the TR nut was frozen... corrosion from all that good humidification? Well after judiciously wicking a single drop of Kroil at a time at the base of the nut (wouldn't want any on the wood) after several drops and a week's time the nut started moving. Lesson learned, I now adjust all the TR's at least annually.
I think I learned there's a reason it's called preventative maintenance.;)

This is my feeling too. The only setups I've ever had done (begrudgingly) have been shortly after buying a guitar and I haven't been able to resolve a minor problem by giving the truss rod a little tweak. We don't have humidity issues in south Florida because it's spot on winter, and the A/C keeps it down indoors in summer.