Presumably, the greater the time period between auctions, the more risk there is for market makers, and therefore the greater cost to customers. I'm sure there

Presumably, the greater the time period between auctions, the more risk there is for market makers, and therefore the greater cost to customers. I'm sure there's a sweet spot that is less than once per day, and greater than continuous. But perhaps determining that sweet spot isn't worth the added complexity, and letting them fight amongst each other over speed is just better for everyone.