Note that only 50% of the fees taken by Ren in any Epoch are paid out at the end of that Epoch. The rest of the fees are carried over into the next Epoch.
So for example, if in Epoch 1 there was $100M worth of value transacted through Ren, $100,000 would be claimed and added to the Darknode Reward Pool. 50% of that (or $50,000) would be paid out to all Darknodes at the end of Epoch 1. The next Epoch (Epoch 2) would already have $50,000 in rewards ready to be paid out to the Darknodes that were active for that entire Epoch. Let’s say that in the Epoch 2, $120M is transacted via Ren, and the Darknode Reward Pool grows by $120,000, taking the total to $170,000. This time, $85,000 would be paid out to all active Darknodes, and the remaining $85,000 would carry across to the next Epoch.