Something about that doesn't look right. The longest one I've had so far is 14 hours. Have any of those that are that long finished for you? Do they really make them that big? That's insane.
Yes, this is normal. Most tasks are very short. But something like 1 in 500 are these super long tasks. Run it exclusively for a wile and you will end up with one running on each core.
"Don't confront me with my failures, I had not forgotten them" - Jackson Browne