Not sure if more frequent/lower millage oil intervals are the key...but i'm doing it aswell since maybe 30.000-40.000km on mine (stage 2 S6 from 2013). Doing short daily trips to work and back, often push it and sadely it often goes hot into the garage (all bad ingredients for sludge or deposites that block the oil screen). Still original oil screen and turbo's with last time i checked still in good condition.
Maybe more helpfull is the fact i do an oil cleaner every 2 oil changes (that disolves sludge and carbon deposits). I used BG oil cleaner but recently steps over to Bardahl as it is easier to be found in my country. Also i add oil booster/turbo protect (adds a fresh oil film onto the metal parts to prevent carbon build up)....in theory but i think it is helping aswell

. Not only i do it for hopefully a good working oil screen and optimal oil flow inside the turbo's...but i also hope it helps keeping the oil cilinder scrapers (or how you are called) carbon free....that is also a hidden over time engine killer on the 4.0TT apperently.