I did a little more on the Merry Cox Shaker Spool Holder yesterday and I'm happier with the flowers now.
I'm mixing the ends of the floss round so, although I'm not wasting any thread, some of the flowers will almost match. It won't look too regimented and not too crazy! Thanks for your opinions - especially Ash, who pointed out that Shakers wouldn't have been wasting thread to get matching flowers. A very good point!
A note for those in the SAL - it doesn't say so in the instructions, but if you want your tent stitches to all go the same way when the box is made up, remember to stitch the sides sideways!