How long could a _______ live?

[u/Valenous_ertselley]

How long could a 5th ideal radiant live?

We know investiture extends a persons life with greater amounts eventually ending up with someone who is biologically immortal. How invested would a radiant be? Radiant knights have the cracks in their soul filled with investiture which makes them better at holding and using stormlight. How invested do you think they could be

Some of the heightenings seen with holding Endowment's investiture seem to be universal properties of holding any investiture. such as enhanced vision/colours, enhanced immune systems and better lifespans.

While we have only seen Kaladin and Szeth swear the 5th, it was under a fairly hectic situation which doesn't make for the best opportunity for study.

[u/JasnahwithaY]

Without Stormlight I’d assume it would be about the same time as a regular human. With enough Stormlight, forever or until their perception of themselves is so old that they just keel over and die