Some technical writers and editors use an acronym, COIK, that stands for "Clear Only If Known." You'll sometimes find that an editor has scribbled "COIK" beside a passage that will be perfectly clear to any reader who already shares the writer's knowledge (and thus doesn't need to read the passage in the first place) but not at all clear to a reader who doesn't share that knowledge.
If the COIK material consists of just a technical term here and there, it can be corrected at the revising stage. However, eliminating COIK material often involves substantial rewriting. For this reason and others, therefore, it's more efficient to avoid COIK material "up front," by making consideration of your audience's knowledge an important part of your planning stage.
This week, before you begin writing each document, think clearly about what your readers already know, and what they don't.