I matted a lot of work when I was in high-school in the 60's. It's all on 'crescent board' - the cheapest board I could find at the time : a heavy grey chipboard with white paper on the display side and blue on the backside. None of this work was stored with any care, and much of it has spent time in a hot attic.

None of the photographs mounted on this board has any evidence of damage. Some of the boards have a slight yellowing around the edges.

If it's not important then there is no point wasting money and environmental resources on expensive board - the cheap stuff seems to hold up for 50 years or so.

If you are selling the work for premium dollar then I agree one should use the best materials commensurate with the price.