Using Allomantic Duralumin to Become a Cognitive Shadow?

[Trusk'our]

When a being uses investiture, they change themselves in such a way that when they die they can persist a bit longer before they move on. So, if someone frequently used bursts of Allomantic Duralumin power, would this cause a bigger enhancement, and therefore change in their soul, to allow themselves to last longer than someone who only burned their metals normally?

[Shard Bearer]

I feel like they would kill themselves before they got far enough to be a cognitive shadow. Didn't Mistborn say that just flaring metals a lot would make you unhealthy, and Spook wasn't doing too well in the end of Hero of Ages. If you burned Duralumin all the time, you would probably just die. 

[Returned]

It's hard to say for sure since we have so few examples. Kelsier lasted quite a while despite not even knowing about duralumin, while Vin passed on to the Spiritual Realm pretty quickly despite having burned a lot of it. Becoming a cognitive shadow for real (like a Returned or a Herald) probably involves more than just high Investiture, even though that is a very important element in the process.

[Duxredux]

Overall I think that burning a whole lot of Duralumin in of itself isn't going to work, but that's more of a gut feeling than anything.

My guess is that in order for your Cognitive self to become self-sustaining without intervention after death, in the sense of you die but your mind lives on indefinitely, you basically need to have held enough Investiture to become an immortal or a majorly warped savant to have your mind so thoroughly saturated with power that it can persist indefinitely even after ties to the Physical Realm are cut. Maybe if you could burn something that would specifically change your mind or increase the Investiture within your mind, such as the cognitive metals or Feruchemical spiritual stores, that might make the process easier but I'm still not sure if it would be enough to do this practically. Unless Allomancy and burning metals are specifically a component of the mind, I don't think that something as general as just burning a lot of Duralumin would cause enough of a change, unless Duralumin Savantism has really weird effects that I don't know about. 

For Scadrial, the only confirmed Cognitive Shadows I can think of all gained power at the Well of Ascension, which doesn't give us much to go off of. There's Kelsier of course, and I think Preservation noted that TLR would have been able to persist if he had so chosen, and that probably includes Vin, both of whom decided to go to The Beyond rather than persisting. So three Slivers, one of whom got direct help from Preservation before Ascending.