Short answer: Yes.
Some manufacturers have salespeople who claim their buildings don't require insulation; that their buildings are somehow self-insulating or that they naturally reflect the heat away and keep the inside cooler in summer than the outside temperatures. I have heard that they claim up to 20 degrees cooler in some cases.
I'm here to tell you this is a completely bogus sales pitch. Quonset huts are amazing buildings, and there are so many good things to say about them that this "insulation optional" hogwash is totally unnecessary and whoever gives this sales pitch to a potential customer should know better. They should sell these buildings on their merits, not on made up nonsense.
Our Quonset huts, before we insulated them, were routinely a minimum of 10 degrees hotter in summer than the outside temperatures. A well insulated Quonset can probably out-perform a comparable stick-built home, energy wise, in my opinion, but an uninsulated Quonset is unlivably hot in summer and cold in winter. The truth is there is ZERO insulation value to the metal shell.
The best insulation for a Quonset hut is closed cell spray foam. The amount varies based on your climate and local conditions, the building code where you are, and your budget.