In my faith path, we say simply that one shall return to Annwn/Avalon/The Summerlands--a kind of limbo, like a temporary version of eternity or Paradise or 'rakuen', but not a 'reward' or a final destination per se--when the Gods call for it, and not sooner or later.
Sometimes you'll go because in your short time you've learned and done all you needed ar y Byd i.e. on Earth/in the mortal realm, or because you've earned a reputation that has won you respect and fame from the ancestors (so this usually would only apply to adults), or because your aura or your skills are wanted at the court/host of the Gods, or sometimes it'll be for no particular reason or for one to which you're not privy (perhaps a God has taken a shine to you personally).
So there could be many factors as to why an innocent or a child or a victim of crime would be called back so soon. Pagan Gods aren't Creators, nor omniscient or omnipotent like the Abrahamic monotheist God, though they're very powerful, superhuman and transcendent. In some other branches of Paganism such as Hellenistic or Norse, every mortal has an allotted life time allowed to them by Fates from their first breath, and when their string runs out or is cut then you must move to the next world--all very organised and bureacratic!
Someone atheistic once asked me what is preventing 'souls' (or whatever you want to call our essence, supposing we have one) from leaving or falling a la Milton, or preventing AI or the like creating a false Summerlands to trick us, and in fairness I couldn't answer, I'm not that smart when it comes theology. All I could reply was that my understanding of the Pagan Paradise is not only as a space/place or a relief from imposed mortality, but a kind of an autonomous and escstatic zone where all souls could unmask and shed their skin and be purely themselves--which is definitely a utopic view only an ASD person would come up with!
Some may find these takes spiritually, intellectually or philosophically childish, but it comforts me. I've had the notion before now that it's actually the concept, hope, yearning and search for such a Paradise that 'creates' it or keeps it alive & real.
