You can certainly finish gathering food for the day/week/month/season. Knowing that you're gathing at X bushels per time period and you need Y bushels to finish out the season, it's pretty easy to figure out when work is over for the day, even if there is "technically" more to do (there's always more to do everywhere in every business that isn't bankrupt and closed, that doesn't mean every hour of every employees day requires more contributions of labor)

There was no food preservation though.

There was all manner of food preservation. Smoke it, salt it, pickle it, ferment it, dry it, thresh it and bag it up in cold storage.