There are far too many collection quests in Northrend to just skip them all in my opinion.

What I did:
- Do quests but skip only the nasty collection quests. Some quest chains are really worth finishing, even if they have slow collection quests.
- When you have built up enough rested experience, go into instances but avoid the ones that give low XP due to having fewer mobs (e.g. Violet Hold and Azjol-Nerub).