5-box leveling, balancing efficiency and "safety" ?

[Apatheist]

From reading many many leveling guides, it appears to be generally accepted that the fastest way to level is some combination of questing+grinding.

Keep in mind that most (all) leveling guides are written by people playing a single character. Many of the quests those guides suggest can take you hours to complete while boxing. Collection quests are a nightmare for us in classic. The quest items have low drop rates, you need a lot of them and you can only loot on one character at a time.

I prefer to use dungeons to level. I run around and collect all the quests then grind a dungeon until I have all of the gear I want and I'm an appropriate level for the next dungeon I want to do. Then I go turn in all of those quests and collect the next lot. Faster than questing in my experience and it allows me to stay geared so that by the time I hit 60 I'm in full blues and ready to start farming tribute runs and other 55+ dungeons.

As a point of reference, an average level 20 quest rewards around 1200XP. An average level 20 elite in a party of 5 rewards around 81XP.
XP = (Char Level * 5) + 45 (elite) * 2 = 290
PartyXP = 290 / 5 * (party modifier) * 1.4 = 81.2 rounded down to 81.

To achieve the same amount of XP as the average quest takes 15 kills in an equal level dungeon. A conservative 90 seconds per pack of 3 equates to 7.5 minutes of dungeon grinding to equal one quest. There's no way you can consistently complete a quest every 7.5 minutes. There's also no travel time in dungeons and the return only gets better as you level up and gain better mana efficiency, gear and AE skills so can start pulling more packs at once.

What might be helpful to the community is for somebody to put together a multiboxing specific quest guide that focuses on kill quests and single item collection quests with high respawn rates or that are group-lootable.

As for being banned, I boxed 5 from classic all the way to the start of MoP and was never banned on any of my accounts despite being reported many hundreds of times no doubt.