@Gin&H As Box is my favorite Hermès leather, I have acquired bags produced over a wide enough period of time to have formed an opinion with respect to your questions. Currently, I have Box leather bags crafted during several successive decades, beginning with the 70s and continuing up through the 2020s.
Since each bag is made by a different craftsperson and each piece of Box leather is unique, my opinion is just that--my opinion. I'm sure other lovers of Box leather will chime in and share their own opinions. I do not consider myself an expert on leather; I am simply sharing my personal experiences.
Characteristics of leather in general, and Hermès Box leather in particular, will vary from piece to piece. When my Box leather bags are sent to Paris for spa services, I always marvel at the ability of the Hermès leather artisan to select leather with attributes that align as closely as possible with the attributes of the original Box leather, whenever any leather portion of the bag needs to be replaced.
My older Box bags are made from leather that is a bit thicker and they have what I consider a more sumptuous quality to the full hand of the leather. Patina will change the appearance of Box leather over time, but it will not change the underlying quality of that specific piece of Box leather itself. In other words, although all Box leather will acquire a beautiful patina with age and wear, a less sumptuous piece of Box leather will not, in my opinion, become more sumptuous over time. The hand of the leather is a completely different quality that is independent from the patina of the leather. That said, Hermès has admittedly struggled in recent years to obtain the quality of hides they require from their various suppliers to produced Box leather bags. To their credit, Hermès will pause the use of Box leather rather than accept inferior materials.
While each craftsperson will become more skilled at their art over time, I do not see a maison-wide correlation between the decade a Box leather bag was crafted and the quality of the craftsmanship of Box leather bags as a whole from one decade to the next. Nor am I aware of Hermès production standards being changed over the decades. For example, I am unaware of Hermès pushing their craftspersons to make a Kelly bag or a Birkin bag in a fewer number of hours now than they did in the 90s.
After all, much of the mystique that continues to make Hermès bags the most desired "brand" of all the luxury houses can be traced back to the maison's extraordinary dedication to hand-stitched, handcrafted bags made one stitch at a time by a single craftsperson from start to finish, culminating in the craftsperson signing each bag they create with their unique maker's code. In my opinion, it is precisely the maison's commitment to these revered time-consuming traditions of
savoir faire paired with their brilliant "marketing" of intentionally scarce pieces and leathers, which is the antithesis of pressuring their artisans to produce more bags in shorter periods of time.
I hope I've been able to share a Box leather aficionado's perspective in a way that enhances your understanding of the questions you are pondering. Congratulations on acquiring a Box leather K28 Hermès bag from the 90s! Enjoy her in good health. Box leather lovers will readily admit that once you've fallen for the allure of Box leather, your desire for "just one more" Box leather bag from Hermès will grow stronger over time. Perhaps there will be a more recently crafted Box bag in your future to allow you to form your own opinion on these interesting questions you have posed!❤️