Fertilizer

One throw skips the wait on a sapling and pops it into a full grown tree. The catch is that the game checks growing conditions first. A sapling that does not have the headroom or the right ground under it stays a sapling, and the fertilizer is consumed regardless. Look at the spot before you throw, because that is where nearly all the waste comes from.

It lands across an area rather than on one tile, so lining yourself up between two saplings grows both at once. Palm trees are the easiest to chain this way because they need less clearance on either side, and you can sometimes catch a third. Paired with the Axe of Regrowth, which leaves a fresh sapling behind every time you fell a tree, you get a wood loop with no waiting in it at all.

Supply is the real limiter. Producing it in quantity means producing a lot of Poo first, which is slow and tedious enough that most players save fertilizer for the moments they want a particular tree standing right now.