Oh, but some things did. For one, you’re able to farm Renown in Torghast, the covenant campaign awards two of it aswell.
As with most things Renown, this depends on how far you’re from the cap. 'till about renown 10, layer 5 will give you one, indeed. You’ll need to go higher after a while. You can start at layer 1 too, but that only lasts a few renown levels, and isn’t significantly faster than layer 5, so not worth the trouble.
Do Torghast 'till about 40, or as long as you can clear a wing within 15 minutes, while it is giving renown. Start at around layer 5, go higher once it stops giving renown. If you’re doing this on your druid, just stealth as much as you can, you don’t need score or anything, just kill the final boss and start again. When I was doing my most recent renown grind, up until layer 7, I was averaging 6 minutes / wing. It became a bit slower after that. But I was doing it on a shaman without stealth… as a druid, you should be considerably faster, since it’s easier to skip, even at higher layers.
Once you’re done with Torghast, do 3 callings (pool them up before switching), that’ll grant you some more renown. Then do the covenant campaign for ~16 renown or so.
If you haven’t completed the weekly 1k anima and Shaping Fate quests, do those as late as possible, since they’re guaranteed Renown, and pretty darn easy and fast.
Between finishing the campaign and reaching cap, spam low keys. Anything between +2 and +5 is fine, the goal is to be fast, so prefer short keys. If you can gather a few guildies or friends to help you with this part, that makes it even faster.
Don’t bother with LFR or PvP, nor normal and heroic dungeons, the renown / hour ratio in those is significantly worse than in low keys.