I am not usually a supporter of people having allocated items in a family. I know it works for a lot of people but it seems too regimented to me and too fraught with potential to cause arguments. I don't even let the children have a place at the dinner table that they can consider to be 'theirs'. Each meal is a free for all and wherever you end up sitting is your spot for that meal but not forever. I am either helping my children develop flexibility or creating children who will grow into people intent on possessing things. I guess only time will tell.
One of my best friends when I was growing up had 4 brothers and sisters and they each had a colour that defined their 'things' within the family. Their cups, towels, lunchboxes, sunhats, plates, etc were all colour-coded. Guests also had a specific colour. I can't remember what the guest colour was now but I do remember knowing never to use someone else's cup for fear of serious reprisals. I suspect that never happened but it seemed like a cultural imperative that was alien to me and for a child prone to anxiety it added a veneer of stress to otherwise delightful playdates and sleepovers.
However, despite all that the mug thing has crept up on me and I think I quite like it. Parenting is a constant balance of things, I often think that being flexibly consistent is what I am striving for. Being consistent and predictable in my actions and words, and flexible enough to realise when things need to change. What about you?