Are truss rods always necessary?

[Shelagh Moore]

I personally don't think a mandolin particularly needs an adjustable trussrod but I do like some form of neck reinforcement and have fitted quite a few carbon fibre strips during repairs which I prefer due to their stiffness/mass ratio. Once things are set up properly there should be no movement of a mandolin neck if CF-reinforced.

[Pete Summers]

I have a 90 year old Regal mandolin with no truss rod. At 70 years old myself, I only wish my own neck was as straight.

Of course, it is the shorter 13 inch scale, so maybe that puts less stress on a neck than the modern 14 inch, I don't know. For other mandolins, I prefer an adjustable truss rod just because it gives me a sense (possibly false) of security, but like others here, I doubt that it really matters much if the instrument is otherwise well made.