If you want to spend as little time on your alt as possible - just do Legion Invasions. You can use sites like (https://wow.gameinfo.io/invasions) to track when the next invasion will be. Log in, fly to the closest world quest, and once there - right-click on the quest's name in your quest log and "Find Group". Sign up for some group, or if there's none - just start your own immediately, and people will come to you. It is 10 times faster to do invasion quests in a group. Once that particular quest is complete - leave the group, and fly to the next one, where you should find another group. Don't expect the group from one world quest to follow you to the next. Then you simply log out until next invasion. You can do 1-2 invasions a day, and each invasion will give you about a level or 1.5 of experience, if you have full heirloom gear. Each invasion will take about 20 minutes.
We’ve spent a lot of space giving advice for those with less experience in the nuances of World of Warcraft. If you’re a player who generally knows how to get around the game—or did at one point—you’re probably still going to feel a little stuck if it’s been a decent amount of time since you last played. For example, why does your favorite weapon no longer work the way it used to? What’s the latest currency you have to know about? Should you ever waste time hanging out in your Garrison again?
I would totally recommend using Zygor's if you are leveling alts or don't care about the quests you're doing, because it offers a huge leveling advantage in terms of streamlining what you do. Just let the arrow tell you what to do and you never have to think about where you're going or what you're doing. When I use this addon (and the leveling guides) I definitely understand why he charges for it.
“For us as game developers and makers of the game, what we want to do is we want to create an environment where players feel like they have the choice to do something meaningful and impactful in the game,” said Cobo. “Ultimately where that choice leads them — is it the right choice? Is the wrong choice? I don’t know — but that’s the whole point, right?
Blizzard tried something new with Battle for Azeroth, releasing the expansion worldwide at the same exact time around the world. That means that while the street date was technically Aug. 14, the game went live at 3 pm PT on Aug. 13 if you lived on the west coast. This is the first time The Americas have launched an expansion at the same time as the European servers. Players didn't have to watch Twitch streams of people who are in time zones ahead of them while waiting for their own launch times. Everyone could log in and start playing together simultaneously.
Tiragarde Sound and Stormsong Valley are both fairly similar zones, but Stormsong is a little longer, meaning that you might not even have to finish it to hit 120. Tiragarde also comes with a bit of a warning. There are plenty of side quests to do in the zone after you finish the story quests. Don’t do them. It’s not worth the time or the experience you’ll get.