The entire point of Severance may be for Helly to become the vessel of past Eagans

Maybe the purpose of having Gemma with so many split chronologies is to try to cultivate multiple personalities in Helly?

We see Gemma dressed as past Eagan CEOs and testing with regards to the barriers.

What if the real purpose of Helena Eagan entering the severed floor is so that each of her split innies can take on the personality or memories of a dead Eagan CEO (i.e. their "revolving").

Mark is chosen to refine Gemma because of their closeness. However, a previous file Mark worked on said "Helly."

It seems possible that Gemma is the lab-rat to justify that having multiple distinct personalities in one person is possible.

Helly is the culmination of this, where the "board" or the past Eagan CEOs can be recreated in each of her innies and essentially "revolve." This would grant the Eagans eternal life as they just train a new descendant with all of these personalities when they are ready, essentially continuing their 'perceptual chronologies."

Once they can ensure that it's possible and reliable for 5+ personalities to be separated by one Severance chip, they can somehow implant the memories or personalities of past Eagans into Helly.