I root in a two step process, in the box for 3 -4 weeks to develop solid roots, then full long fiber moss in closed cups for another month until the moss is covered with roots, you can see pictures of various stages in my previous posts. No, I do not cover the wood completely only slighty, the goal is humidity not soil media. As you state it can be done in covered moss but if not watched very closely the risk of root breakage is high. I find this two step pure moss process has the highest success for my set of conditions and time. The high root mass I get is key to success in the 1G pots later on and mimimizes lower humidity leaf wilt in the 1G transition for me.