Minecraft wiki entry for Tips_and_tricks, associated text: For fences, you will want a multiple of 5 logs. Convert them to planks, then convert one-fifth (1/5) of the total to sticks. With 20 logs, you can just turn the smaller stack of 16 planks into sticks, then craft that with the other stack of 64 planks, for 48 fences.
By comparison, fence gates are easy, and cost exactly 1 log each. Convert the logs to planks, then convert half of the planks to sticks.
For ladders, crafting 7 logs at a time into sticks will let you just drag the resulting pile into the ladder shape, for 24 ladders.
If you have a lot of spare sticks, a stack of them will make 27 ladders with one leftover.
For slabs, doors, or trapdoors, multiples of 3 will come out even, (Likewise for stone slabs and walls.)
Chests cost 2 logs each. Crafting 16 logs will get you a stack of 64 planks, which you can drag into the box shape to make 8 chests at a time.