I was referring to the external bandwidth. Even if pulling down a request takes hours, forcing them to start off peak will significantly shift the impact of the incremental demand. I'm guessing that most download requests won't be for your entire archive - someone might have multiple months of rolling backups on Glacier, but it's unlikely they'd ever retrieve more than one set at a time. And in some cases, you might only be retrieving the data for a single use or drive at a time, so it might be 1TB or less. A corporation with fiber could download that in a matter of hours or less.
I get it - but I'm arguing that the amount of egress traffic Glacier customers (in aggregate) are likely to drive is nothing in comparison to what S3 and/or EC2 already does (in aggregate). They'll likely contribute very little to a given region's overall peakiness.
That said - the idea is certainly sound. A friend and I had talked about ways to incentivize S3 customers to do their inbound and outbound data transfers off-peak (thereby flattening it). A very small percentage of the customers drive peak, and usually by doing something they could easily time-shift.
