The adaptations will occur not at particular number but at range. If yo have not bumped up 10-20W (what can happen sometimes, especially when you start with structured training) the adaptations will be similar even with a little bit lower FTP. If your workout was Galena +3 , 4x20 min@90÷ FTP is not prove that your FTP have improved but your muscle endurance. Wait for other workouts and check how they feel. If you want to test do Kolie Moore’s test - at least it is also a very nice workout.