As you level, you will buy new ranks of spells. If you splurge out on an item upgrade, you will not have enough gold readily available to upgrade to the latest ranks of spells: placing you behind. Moreover, you can buy gear upgrades from the Auction House (AH) or vendors. Furthermore, you may have large investments that need to be paid for professors. You will need to purchase reagents and items such as leather, bolts of cloth, alchemy supplies – unless you have a charitable friend or another high-level alt.
Escort quests can take awhile to do. I have thoroughly tested all the escort quests in the game for time/xp. Most are worth doing, but as long as you are able to actually do them without failing. Most require you to pay special attention to the escortee as most are fragile and will die easily, so do your best to keep mobs off of the escortee during escort quests. The longest one in the game is the Tanaris chicken escort. The chicken escorts are only worth doing if you were able to do all 3 of them, as if you do, you will be able to turn in an additional easy quick XP turn in quest at BB, which makes them worth it.
I am currently working full time on my Vanilla WoW leveling guides. Soon there will be a 1-60 speed leveling guide for Alliance, along with in-game guide versions available for my members area. As of right now, there is no members area, but if you would like to show support for my efforts into this project, you can simply donate to me via Patreon if you like (you will get some cool rewards in return). Or you can donate directly with PayPal if you like. All donations are highly appreciated and they will only motivate me more to continue making the best vanilla WoW leveling guides on the web.