I might be the only one when I say that but when looking back at the first three seasons I always felt like that the mountain passes and races had some sort of identity, something that made them special, unique and therefore entertaining to watch.
You surely remember Akina with it's 5 consecutive hairpins or Usui Pass with Takumi's extreme endurance race againt the Sil-Eighty Duo or the AE86 vs AE86 race on that very old and horrendously maintained pass. However here, I can barely recall any race because they were lacking in identity. Unlike in the first three seasons, none of the mountain passes were introduced properly and there wasn't anything special about them. This wouldn't even be a problem if you wouldn't be thrown at with totally random and partly pointless characters that ALSO get barely introduced and just serve as race fodder for Takumi and Keisuke.
But without interesting tracks and characters to race against, all the races just feel boring. Then it doesn't make it any better that you basically get no break between them. It's literally race after race after race after race. The amount of more chill filler episodes featuring older characters like Iketani or Itsuki has been greatly reduced. Some might say that is a good thing but if I am honest in this long season more screen time for these characters wouldn't have been a bad thing.
However, there are exceptions. The first and last race are actually good and don't have these faults. Another positive thing about this season is also how deep it goes into racing, driving style & technique etc. It's not hard to see that this season is focusing heavily more on that with Ryosuke acting as a mentor for both Takumi and Keisuke trying to give them tips for their upcoming races (even if he basically starts speaking in riddles which is something i don't really know if I should like).
Apart from that Initial D Forth Stage is also building up towards a fight between Takumi and Keisuke sometime in a later season, something I really can't wait to see (even if I think I already know the result :D)
In the End, the forth stage of Inital D is still enjoyable but very repetitive and therefore quite a letdown. It just doesn't have the magic the older seasons had and instead just tries to include as many races as possible in 24 episodes which just wasn't a wise choice.
