In the remake of Hawaii Five-O, Det. Danny Williams seems to be routinely absent; occasionally they'll offer some kind of explanation (e.g. the fact that he's in the hospital recovering from donating bone marrow to his son), but more often than not it seems like they won't even comment on his absence. Why is this? Why is he absent so frequently?
Apparently, because the actor (Scott Caan) asked for a reduced role. Here's his answer to this:
"I do five episodes less than [series star] Alex [O’Loughlin]," said Caan, who lives in Los Angeles while the show shoots in Hawaii. "I just do a couple episodes less so I can come home to see my family and stuff. They were cool about it so we just all came to that."
Another source elaborates:
Unlike some of the show’s stars and guests who have made themselves at home in Hawaii, Caan continues to live in Los Angeles. [...] Caan has a daughter born in July 2014 and activities outside “Five-0” including a play he wrote, “The Trouble We Come From,” which was performed in Burbank in 2015.
So it seems Caan is too busy with other things and prefers living in Los Angeles rather than Hawaii (he actually got in a bit of trouble after expressing that preference).
That's what the actor wanted.
Scott Caan confirms...
"I do five episodes less than [series star] Alex [O'Loughlin]," Caan said, according to Post-Gazzette. "I just do a couple episodes less so I can come home [to Los Angeles] to see my family and stuff. They were cool about it so we just all came to that."