for 5 mans, pvp, ubrs I agree that there’s a lot more than just shadowbolt spam, however for 40 man (and likely 10 man) raids you likely can’t use corruption or shadowburn because of the debuff limit. I remember back in vanilla my guild thought that the boss just didn’t show all debuffs, not that it was limited so there’s no telling what debuffs the bosses actually ended up with, but now we know better. As nice as it would be to keep corruption up for personal dps it’s just not worth it.
Shadowburn is a maybe, but would only be used right before the boss died or you could clear off an important debuff. At that point it’s not really making a difference unless you’re having one of those fun wiping as you kill it kind of fights, in which case every single spell matters.
As for deathcoil I would prefer to use that defensively and spare healers some mana, or pop it when you life tap so… fair point there.
The only thing you didn’t mention is soul fire, which I think, THINK doesn’t add a debuff and might be worth casting if you have the 4 second cast talent.