The TLDR is that the design of b^e means that (other than the root node which you can store in RAM), you never need to write in chunks less than b^e (smaller wr

The TLDR is that the design of b^e means that (other than the root node which you can store in RAM), you never need to write in chunks less than b^e (smaller writes get batched and pushed down the tree only when you have that much data to write to a child node). With the typical, e=1/2, you can set b=blocksize of SSD^2. This means that any small write will turn into 1 write per depth of the tree, and each of those writes will be writing a full block of data (so the maximal WAF is the depth of the tree). Also, for bigger writes, you can just write to the bottom directly, so this ends up working out such that for large sequential writes, you get a WAF of 1, and for small/random writes, you get a WAF of d.