Its not a failure or success. Just different outcomes of your decisions or skill.
There is no favoring of a specific way to "solve" anything here either.
And you actually do not need to get every last point of Xp, nor you can - at all.
Its not actually necessary to grind and max out XP, the game is perfectly playable without it.
Since i restarted the game more then 20 times so far i usually skip various smaller sub quests or specific solutions regularly and it doesnt create any problems at all.
