Diablo IV players experienced server queues during the recent early access beta, and Blizzard boss Rod Fergusson has explained why they happened and why they are sometimes necessary. For context, server queues on the first day of the Diablo IV early access beta could be upwards of two hours, but by the end of the first weekend, server queues were practically nonexistent.

Speaking to Eurogamer, Fergusson said it would be ideal if there were no server queues whatsoever, but that is not always possible nor may it always be in the best interest of the game. Fergusson explained that sometimes server queues are due to high demand, but other times, queues are put in place even when a game's servers are not at capacity to help with specific subsets of a game.

"Sometimes you'll put a queue in place just so that if there's one particular service--like writing to the database--that you're trying to not overwhelm, you'll add to the queue to say, 'Hey let's just slow down a little bit while we fix this or look at it,'" Fergusson said. "So it's not always just availability of space. Sometimes something's being investigated, or you're trying to manage pressure on one particular thing until you can reinforce it."

That is what happened with the Diablo IV early access beta. "We actually turned up the queues a little bit to protect this while we were working, and then, once we did the work, we were able to start dialing it up and dialing it up and the queue was going back down again," he said.

Fergusson pointed out that server queues are an "inexact science," but the aim is to be more conservative out of the gate in an attempt to mitigate issues later on.

"You don't know how slow it has to go to not fall over and so you go conservative immediately. And that's what people were seeing through the bigger queues when we were being very conservative, to say, 'We fell over once, we don't want to fall over again,'" Fergusson said. "And then, as we started to work and gain confidence, we started to go, 'Hey let's halve the time. OK, let's halve it again.' So eventually it goes away to nothing."

Diablo IV's open beta runs from March 24-26, and given that everyone can get in, more server queues are expected. More than 1 million people played the early access beta and unlocked a very adorable wolf pup item by reaching level 20.

For more on the Diablo IV beta, check out GameSpot's Diablo IV guides roundup to get the lowdown on everything you need to know. Progress from the early access beta carries forward to the open beta, so players who got into the first weekend can keep pushing ahead with their existing characters. For more, here's everything you need to know about the Diablo IV beta.

Diablo IV releases in full on June 6.