It really doesn't matter.
Most if not all of the metal aircraft that were built through the 70's
were not zinc chromate, so inter granular and other types of corrosion
are still problems with any aircraft, be it stored in a hangar or at an
outdoor tie down.
With fabric, you will want to recover it every 10-20 years just so you
can perform a thorough fuselage, wing and empenage inspection.
Much easier to inspect and repair than on an all metal aircraft.
Many of the older rag and tubes have gotten powder coated or epoxy
painted frames if they have been rebuilt in the last 10-20 years.
It all comes down to personal choice. What do you want to do with the airplane?