Unlike the crafting recipes for other wooden items (i.e. stairs, slabs, etc.), the crafting recipes for signs in the recipe book are not grouped together as a single icon that periodically changes between all the wood types.
- Put a stack of sticks and a stack of each type of plank into your inventory.
- Open a crafting table. Open the recipe book. Check the box in the upper right corner to only show currently craftable recipes.
- Type "stair" into the search bar. See that the recipes are grouped as a single icon.
- Type "sign" into the search bar. See that the recipes are not grouped as a single icon.