I was myself mislead by the documentation on more than one occasion, see e.g. Task-Condition issue, so when I wrote that something implied by omission in some help page resulted in “hardened convictions” I did not mean to assert the fault lies with the person who read the said documentation…
Probably a good approach would be for the various clocks help pages to refer the reader more explicitly to superclass Clock page for the overview of what can be sensibly scheduled on a clock. Well, ok, those sub-pages do say:
See Clock for general explanation of how clocks operate.
The varying terms used in those sub-pages like “task”, “item” etc. could probably deserve some reconsideration as to whether a single one should be employed uniformly or at least some notice be given ahead that that or those are generic terms whose instancing is explained in the main Clock page.