It is definitely more than 1 per hour. I planted Nexus Nuts on 7 farms overnight and just harvested them. I had fulfilled the requirement before I was done harvesting (35 planting hours for 65 runes). BTW, I got a rune last night on a round of Upgrapes.
In past World Events I have not always gotten pop-ups when collecting food even if I collected slowly, but I still received the tokens. I wouldn't worry about not seeing the pop-up notifications.