I have 2 suggestions that i’ve wanted since legion, i know that dugi is meant for getting as much xp as possible as fast as possible so what im about to say might be done intentionally.
1st: The leveling guide doesnt contain all main storyline quests in some zones, an example for this is zangarmash in outland. If you complete all steps in the guide including the quests that require reputation you get 6/7 chapters, you need 2-3 more quests to get the final chapter (a trip with the sporelings) that arent in the guide. This might be on purpose since there are quests that require alot of work for the reward they give which isnt worth it and for leveling this is good but it causes a problem when you are trying to get achievements like loremaster since the achievement guide simply tells to complete the leveling guide.
2nd: This suggestion is the opposite of the one above, certain leveling guides contain quests that arent required for the main storyline. The best example i found is the suramar zone, i had to complete the main storyline for broken isles pathfinder in order to get flying unlocked in legion and the guide told me to complete the leveling guide like always. So i decided to look up the achievement in wowhead and wowpedia and both websites show a questchain that is much shorter than the leveling guide in dugi, i would have done dozens of unnecesarry quests if i had followed the guide in dugi. As i said this is probably on purpose to get the most xp possible but it’s not efficient for achievements
My suggestion is a different version of the leveling guides that only contain the primary storyline and nothing else, there can be an option to chose between different modes in settings or it can automatically chose depending on if you get directed from achievements tab or leveling tab.
One last note: This is not a serious issue, i love dugi guides and i will keep using it for lots of stuff this is just a nitpicky suggestion.