Unholy - Questions Regarding AOE Rotation, and "Always Have 3 Runes Recharging"

[Graveworm]

I have a couple of questions regarding Unholy. Firstly, I have referred to Icy veins on multiple occasions but it seems some people do things differently. If there are 2 targets do we do do our standard Outbreak/FS/Soul Reaper/Apoc rotation into D&D Scourge Strike Spam? Do we still use SD procs/Use death coil at all? When doing more than 2 targets I've read some people just Outbreak/Epidemic Once/D&D and spam scourge strike and ignore Death Coil even while over capping, so I'm not sure whats best. Secondly, I've read people saying to only ever burn 3 Runes, what is the reasoning behind not burning all the Runes when readily available? And lastly, it seems people take All Shall serve, Bursting Sores, Ebon Fever at different times times. All Sims show All Shall Serve being used but looking at top DKs such as Infeh he never takes it and rotates between Bursting and Ebon. (I should mention I strictly do Mythic+ 5 Man's and don't have time to raid) If any of you experienced DKs can answer my questions I would greatly appreciate it. Thank you.

[Dahti]

For 5 mans pretty much never take AWS, pair ebon fever with epidemic (imo) for instances where you know there are a lot of 4+ mob fights. Otherwise go bursting sores and PP (I find this build to be more flexible). Castigator seems too good to pick clawing shadows. Though they perform similar. Infected claws can also be somewhat viable if you have a sludgebelcher. When transformed they can apply the debuff with aoe, frees up FD runes as you just tab through and SS.