My comics-teacher in college used to tell us that we don't have to draw every single brick! You just have to draw a few, scattered over the surface, to imply that there are bricks there, and then your reader's mind will sort of fill in the blanks.
Here's an example of what I mean. It's a panel from a Donald Duck-comic, drawn by Don Rosa:
Notice how he's drawn some of the stone slabs in the fortress walls, but he's left gaps between the lines on some of the towers, in essence leaving some of those stones "incomplete"? Your brain is still filling in the gaps, imagining that the stones are there. Don Rosa didn't have to draw every single complete stone; he just had to draw enough lines and minor details to imply a stone-wall surface.
This isn't an easy trick to master, but it's worth trying, because if you can, it'll make drawing complex stuff SO much easier.