I don't make a lot of rectangular boxes these days, but the linear requirement to do a continuous grain box adds up pretty quickly. Following Fibonacci's ratios, a 12" box front has a 7.5" box end--so if i'm absolutely perfect i need to resaw a 20" board to get that proportion in continuous grain in all 4 corners. That's a big box, but for things like our grandchildren's keepsake boxes i think i did the interiors at 12.5" x 9" so their parents could fit paper in flat. So the exterior board would have been 1.5" thick, 25"+ long, then resawn and cut sequentially to make the 4 sides with continuous grain in all 4 corners. Did those at 8" or 9" deep if i recall (been 7 years since the last one!!), and cut the lid off on a friend's Byrne's modeling saw to save the grain from that kerf.
Continuous grain looks awesome--but it's one of those things that only a fellow maker would ever see. But i still grin every time i see those boxes on the shelves of our sons' homes. Should take some pics some day!!