$30,000 * 0.75 = $22,50, meaning the user can borrow at a maximum $22,500 worth of assets before being liquidated.
$20,000 / $22,500 = 0.8889.
$28,000 * 0.75 = $21,000, causing the Vault's health to be
$20,000 / $21,000 = 0.9524.
$26,666.67 * 0.75 = $20,000, causing the health ratio to equal 1, thus making it eligible for liquidation by KeeperDAO Keepers. From an external Keeper's perspective, the position is still not liquidatable due to the buffer provided by JITU. A KeeperDAO Keeper performs the liquidation on the Vault, without having to compete with any other Keepers in the wild, significantly increasing the profit margin for the liquidation. A share of these profits are then returned to the user who's Vault was liquidated, resulting in a best-case liquidation scenario for both the user and Keeper relative to liquidations in the wild.