When I built my earthbag foundation I found that wet bags were superior to bags that had drier mixes. I think I read in an earthbag book once--don't remember which one--that the wet bags when tamped bonded the sand and clay better. This is also the experience when doing cob too. I did remember this website
https://www.northernarchitecture.us/earthbag-building/the-dirt.html that talks about "weeper bags", and that they found them better to dry harder than traditional drier mixes as well. When you tamp a wet bag, they seem to not compact quite as well due to the liquid content, so you end up with a less flat bag. You want to tamp the bags the same day they are filled. I would lay down twenty bags, then tamp to use different muscles.
Depending on your weather, the bag should feel pretty hard after a few days of drying in warm weather. Obviously the cooler and higher humid the climate, the slower they will dry. All I can say is that after I finished my earthbag stemwall I accidentally backed into it with the hitch on my truck and it only ripped the bag and didn't do anything to the wall. I was using roadbase mixes from a local quarry.