They should switch to logarithmic scale and just say "an order-21 time interval". These "zepto" prefixes are gibberish.
On the other side, we're all very used to mega- and giga- and tera-, and for data center folks, peta- as well, and we'll adapt to the higher-order prefixes as they enter more common use.
And we're not asking the layman to know all these, either. Zepto- will never be in common use; that's for particle physicists and basically nobody else, so far at least.
Everyone already knows 10^12=tera, so we're covered there.
I think the number of people who could (correctly!) name even half of those is much smaller than you think.