This is the easy bit, it's the carapace, mainly the vents that get wearisome as I'm fast remembering.
I really hate those vents, when I've got some of the paint left over I'm doing the no brainer items, like the top of the vents and ridges. All the other striations require some thought how the shapes fit together and interact with the shape of the part of the model they're on.
I also got some of the bone highlights finished on weapons too. It's easy to forget these need doing as well and they're big pieces too. They're bigger than Tyranid Warriors for example!