Efficiency only matters when comparing packs with contents you need. Anything that collects dust in your inventory is zero efficiency.
We are also doing the same calculations for paid and free leafs. This means efficiency would change based on player spending, so please use as reference and always check if a pack is worth it for you.The following items are currently unrated. Some may be rated/approximated later, but require significant theorycrafting:
Lastly, huge thanks to @archlams since he's the one making the sheet to make this page possible.