I'm not sure what buckets you're talking about. Can you give me a little more description of your setup and how you feed them.
Most commercial farmers maintain shallow beds but not all. You said, "very moist" and that means wet to me. It should only be just moist like a damp sponge.
This allows plenty of oxygen at all times. If it's too wet it will take too long for the bin/bucket to dry creating unfavorable conditions. But if you could give a little more info and maybe some pics that would be great.
You don't have to upload pics though if you're wanting to remain a little more proprietary.