My method is as follows: Do your weekly Guild Accommodation granting events. Guild Rush, Trek, JP, Bounty, w/e. Some grant accommodations, some do not. Use those accommodations to purchase Heroes Banners. Go into EotM. Check out the commander/zerg and see if the map has a solid rotation of node swapping going on. Hopefully, the map isn’t full of useless halfwits that want to zerg vs zerg on a karma train map. If it isn’t going well then switch maps. If it is going well link Hero Banner in chat and let the map know its at spawn. Coordinate this with the commander so time and progress isn’t wasted.
Utilize any buffs you can. Guild buffs, food buffs, gemstore karma buffs, etc… to stack karma increase. Then karma train like its the end of the world. Be polite to your commanders and zergs but try to keep everyone on track and avoid enemy zerg confrontations as much as possible. Maybe buy your own commander tag and learn the ropes to lead your own k-train.
The more zergs confront each other on the battlefield the more likely it is that one force will begin to turtle/defend keeps halting a great deal of progress. This can be extremely frustrating for people that have little time to play during the week and want to make the most of the game.
You can make a great deal of karma this way which can then be used to either convert into any material regardless of tier. There are a few forum posts consolidating info on karma conversion as well as some posts on Reddit that are useful. You can also convert karma into Obsidian Shards which you use to make mystic clovers. Making mystic clovers gives you a great deal of T6 mats. Even if you don’t need mystic clovers this is still a great way to make those mats in bulk.
The key to this depends on keeping people focused on karma training. Many commanders don’t understand that if you force zerg battles on EotM karma train map then the karma train will slowly jump back into WvW maps upsetting a large portion of the population that care about the scores in WvW.
This is just my personal favorite way as it seems to me to be the fastest method as long as your team can stay focused.