Prior to update 7.3.5 it was far too easy to level up a new character. The experience needed to advance from one level to the next was too low, resulting in players out-leveling the story quests in each zone, moving on before getting the full experience. With low monster health and high player power (especially when players were outfitted in ridiculously powerful heirloom gear), creatures dropped like flies. Combined with easy experience gained by joining parties in the dungeon finder, the first 60 levels in the game flew by.
5% was admittedly an exaggeration, just felt that low. I'd say it was probably closer to the 30-40% range. It was Artifacts of the Blacksilt, spent a good 10-15 minutes killing Blacksilt Seers to get two damn idols to drop. A quest that had me killing Elder Brown Bears for bear flanks also took quite a while, though that was less due to drop rate and more due to how spread out they were.

As you're leveling, I generally recommend you just follow the natural flow of the progression through each zone. They're laid out fairly reasonably. But don't be afraid to hop around, especially if you're near a quest objective. You shouldn't actually need ALL of the zones listed to reach 62. Pick the ones you like best. It's much more important to simply be as focused as possible and flow from one quest to the next.
The reason for this is simple: Most players don’t need a lot of gold or care very much about it. An active player might earn an income of a few thousand gold per week from sending followers on missions and doing World Quests that award gold. They might then spend most of that money at the auction house buying things like flasks and stat-buffing food to do raids and Mythic+ dungeons. Gold just isn’t a big deal for them.
You should equip new quest rewards when their item level starts beating out your previous set of gear. If you are currently wearing Tier 21 gear, it is best to let the quest rewards significantly beat your existing item level before using them. With that said, you will unlock Azerite pieces early on, which are worth using over Tier gear in most circumstances.
For reference, my previous best time abusing Method-0 in 7.3.5 was 32.4 hours(as show in the old thread). A difference of just over 8 hours; which isn't all that bad, all things considered. And I believe I made several errors along the way, which could be cleaned up in future runs. I believe that that gap could be significantly closed by using a monk's bonus, but I hate playing YMMV
Our deliveryman buys the object you put on sale in the auction house in the game to perform the delivery. After placing your order on IGVault, if you “Auction house” as delivery method, you must also choose one of the objects that you are about to put on sale in the game as well as its quantity. (To find the object rapidly and to accelerate the delivery, we have put some common objects in the menu for your choice)
With the level cap being raised in each expansion, new players are faced with a rather long and dated leveling experience until new level cap is reached. Blizzard already implemented stat squishes through the Battle for Azeroth 8.0 pre-patch last month, and has further lowered the amount of experience required to level, but even Blizzard believes that new players aren’t getting the leveling experience they deserve.
I used fully upgraded and enchanted heirlooms; missing only the fishing ring. Leveling from 1-20 took ~3 hours, at which point I immediately turned on War Mode for the duration. I rarely encountered enemy players, and when I did they almost always left me alone. But the few times I did get ganked, the total cost in time was insignificant. Maybe a total of 5 deaths from ganks in the entire 40 hours.
Edit 20 It’s been a week since this post and a lot of people are still reaching out to me with questions which is fine. I have had a few different people reach out to me to help make YouTube videos based off this guide and more info in BFA which I’m more than willing to do. Whoever gets the videos up first I will link them here for you guys to enjoy.