Sostratus
Deity
Pretty much everyone I know who plays civ6 at a less than deity/fast win level gets very excited about placing districts with good adjacency. As a fun generator, it is fantastic. And i also think that it's something the game should reward. Yes, some of it is luck based; but so it finding an amazing spot for petra or St Basils or Temple of Artemis; people love pulling those off. The district adjacency cards, for the most part, do very little compared to the monster Building cards. And two of the districts which lack building cards have buildings that tie with adjacency - the IZ's coal plant and the Harbor's shipyard - which are also very fun and rewarding to place. "He's doing so well because he placed his districts well!" is exactly what you want to promote.Policies that double District Adjacency.
I think the big problem with the abuse cases (like aussie or the seowon) is that almost every district's adjacency is fully available from turn 1. Campuses get full benefits from mountains and geothermal fissures immediately. They also mostly come extremely early. Whereas to get bigly numbers on the IZ, you require aqueducts and canals and dams to be unlocked, and also built to benefit from them. But IZs also don't show up until the middle ages. If they pushed back campuses 1-1.5 eras, and moved the +2District Adjacency is heavily under-developed. The policy issue is entirely separate, and is largely due to how spawn-reliant some districts are, or the absolutely absurd numbers that some civs can easily generate. Australian campuses are the easy example.
I really like the idea of districts as a 2D city planning element, but there's so so so much more that could have been done to make it interesting.

Edit: Imagine in this alternate world that campus and some theater buildings improved the per pop science & culture output instead of grants tons of flat yield. Totally different ballgame even it it was adjusted to keep the game pace relatively similar.
Think of it this way.
A good IZ might be +6


A +3




Add in craftsmen and natural philosophy. Now the IZ is equal to about 4


Campuses and theater squares are unbelievably pop efficient districts because they set districts' yields to roughly have






But no one here is saying IZs are problematic, even though they can with some ease develop far high adjacency than campuses ever will.