what am I missing?
Ouroboros Praos divides time into epochs. Each Cardano epoch consists of a number of slots, where each slot lasts for one second. A Cardano epoch currently includes 432,000 slots (5 days). In any slot, zero or more block-producing nodes might be nominated to be the slot leader. On average, one node is expected to be nominated every 20 seconds, for a total of 21,600 nominations per epoch. If randomly elected slot leaders produce blocks, one of them will be added to the chain. Other candidate blocks will be discarded.
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Thanks, but I was already aware of that information. My question is still unanswered.
In any slot, zero or more block-producing nodes might be nominated to be the slot leader.
This means that all the slots that do not appear are because they had not slot leader?
Exactly, on adapools.org u are seeing only the leader slots (21.600)
Yeah, this video was very clarifying