On the Audis we have, the seat cushion and the seat back`s cushion (and the part of the arm rests your arm rests on ) are leather.
I`ve found that in many (most?) cases, once coated leather gets worn a bit it does give every indication of benefitting from a Conditioner. Sometimes the apparent improvement is downright dramatic, other times it`s subtle. And yes, on newer leather it sometimes it appears to just sit on the coating and do nothing beneficial at all...but a few years later it`s a different story.
IMO, unless you`re talking about a convertible in AZ or somesuch, the whole UV Protection thing is a non-issue. Little UV penetrates today`s autoglass and interior materials are pretty tough.
Short version: IME most of the time all you need to do regularly is keep leather clean. Dirt harbors more dirt, and dirt causes accelerated wear.
Our Audis: I hardly ever condition the leather in any of our three Audis, though I`ll *sometimes* do it to the `93 if it seems to be drying out/getting stiff. That car`s leather was just a *little* stiff when I got it, after 15 years of *never* having been conditioned/treated/etc. My wife`s `00 A8 has ~160K on it and gets used hard, hauling kids, elderly people, and sometimes even pets (i.e., it transports people/things that can be awfully hard on interior surfaces). Its leather is also fine despite only having been conditioned maybe a half-dozen times since new (and not at all recently, been years). My `01 S8 hardly counts as it`s a garage-queen, but I`ve conditioned its leather maybe three times at most. So while YMMV, I just don`t find my Audis need much of anything, other than being kept clean.
The beater-Tahoe: I hadn`t conditioned its *VERY* worn leather for years, probably haven`t done it properly since I got the thing. I did a real quick slap-dash job of cleaning/conditioning it and it did get softer and more supple. Note this vehicle is used *VERY* hard and hauls big, active, dogs on a near-daily basis.
All those vehicles have "coated leather". Every one of them benefits from the conditioning that "shouldn`t work due to the coating", but to varying degrees and I sure don`t feel the need to do it very often. I hardly *EVER* do anything more than just wipe things down with an Interior QD and maybe treating the S8`s leathe with some Leather Doctor Protectant if I`m in the mood (not like it actually needs it).
(Regulars here will note that I haven`t mentioned my long-neglected, still-mothballed Jag

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One thing I will caution about is overdoing the application(s) of Conditioners. When they build up it can be a nasty mess that retains dirt (leading to accelerated wear) and it can happen so gradually that it`s not always obvious. So I`d be a little careful about constant use of Leather AIOs (no, not hating on them at all) and I`d clean any leather before using a conventional Conditioner on it.