Papercuts
Some tasks are small and hard to justify as worth doing.
They get pushed to the back as chunkier and more valuable tasks get priority. Soon there are a thousand tasks left undone, compounding into a mess that out-chunks anything else.
With a thousand papercuts, the environment in which to get work done becomes sharper and work slows down.
I keep a list of these papercuts and fit them in: Before lunch, Friday late afternoons, and before a next chunk gets momentum.