Not sure if you read this, but this is what happens in Classic and once you get higher, you will face even more grind between the guides. It’s normal. I’ll strongly encourage that you don’t let yourself fall behind. Grind/do Dungeons + Dungeon quests etc. Whatever you can to catch up before you switch guides. I myself try to kill as much as I can and if it’s not enough, I find grind spots and stay there until I ding (I don’t do Dungeons atm. so I’m usually faced with more grind than the typical player).
@Tcahuzak luxury problem. I’d stay in that guide until everything turns grey. Read my link. As long as you’re still within 5 levels of the quests or they’re green (in most cases), they still give the same XP when you turn in. Just pull more mobs at a time if possible. Enjoy being OP for a bit. Or switch to a higher level guide, if they turn grey. You will catch up, unless you do Dungeons, so don’t worry.
About to hit 2 x 60 and a couple of alts so far.