Every 5 minutes of uninterrupted uptime adds to the weighted amount (credit) for each staking period.
Every 10k IDEX token staked per 5 minutes earns 1 credit. Fractional credits can be earned (e.g. 11.5k IDEX token would earn 1.15 credits).
For example, if you staked 10k IDEX token for half of a full period, you would earn roughly (14 day period/2 * 24 hours * 60 minutes * 1 credit) / 5 minutes = 2k credits.
Tier 3 stakers earn 50% of all ETH earned by IDEX. At the end of a staking period, fees are distributed to users based on the percentage of the total credits they earned within a period. For example, if a user earned 1% of the credits for a period, they will earn 1% of the payment for that period.