1 Shot Campaigns, and throw away characters.

[1QD]

If pre-gens are provided, or if character generation is dirt simple and very fast, then one-shots can work just fine.

It seems the OP's concern (if I'm reading it right) is around situations where a player spends an hour or two creating the character to then only play it for about an equal amount of time.

Yes that is my concern. As mentioned I do have prerolled, but character creation, at least really great character creation, takes time, thought and planning. I expect 1st time characters to be somewhat underwhelming, as people are still learning the system. 2nd Gen character will almost always show dramatic improvement. That said, my go to, is epic, world saving heroics, so one offs are not a specialty for me.