A multiple of 30 means you are paying 30x times expected...

A multiple of 30 means you are paying 30x times expected earnings. For a business that's not growing, and paying out all its earnings in full, that means you will get your money back in 30 years (in nominal terms). So even if next year's earnings and the one after, were to double, you'd still have to wait 28 years to get your money back. So how significant is that?

But for a business that reinvests a large chunk of its earnings for growth, such as ARB, I suggest it's even less significant. The value of a business that is growing will be more heavily weighted to earnings further in the future, which will be less sensitive to near term ructions.

Of course, if you think COVID19 has created a sustainable step change in ARB's earnings power, then that's another matter.