How long is the duration of an Epoch? A specific amount of produces blocks?
An epoch is 432,000 slots with a slot being a target rate of 400ms.
432,000 x 400ms = 172,800 seconds / 86,400 (1 days) = 2 days
This is approximate slots target 400ms but are usually a little slower. So an epoch is around ~2.5 days.