One word: DRYWALL.
When furring in the windows, we almost made the huge mistake of mis-attaching the furring strips.
For the sake of example, let's say we started in the right hand corner of a room and were laying furring along the wall to the left. Since we'd never done this before, we started with the assumption that when you started from the corner with the first furring strip, you'd measure from the exposed edge (the left side of the 2x4 ) of the corner 2x4, measure over 24" to the left, then lay the second furring strip to the right side of that 24" mark. So far so good.
The question was what happens when you come to a window, or a door frame. What then? I thought, well, you just frame in the window on all four sides, then continue measuring 24" to the left of the left side of the window and start measuring 24" from there. WRONG.
Apparently, you need to keep the 24" pacing around the wall and room, regardless of what gets in the way, because of the drywall 4'x8'measurements. So, if you need to add more strips around a window or a door frame that is not at a pre-measured interval, you just add in new furring where you need it.
In the animated image here, I've shown what we did, and why. CLICK THE IMAGE.
Note (in the animation) the orange arrows show where we added in the additional furring to the left, above and below the window to accommodate the window, but did NOT adjust the 2' spacing of the regular furring strips, and how the drywall would be laid in (from the ceiling downwards) after everything was in place.
Again, I note: In the 'preview' image, it doesn't show the animation, so you'll need to click on the image to see the full presentation.