UI consistency versus UI variety – opinions? [closed]

I used to tried to make make my UI very consistent, now I am wondering if that is actually good. I chose consistency based on the user only having to learn things once. But now I am having doubts. I had a dropdown and next and previous icons. Was used for 'sections' and 'sub-sections', but a user had an issue realizing the dropdown and icons were re-used for navigating 'sub-sections'. Providing a totally different look for 'sub-sections' UI views seemed to make things clearer. Just curious if anybody else designing has questioned that choice and what conclusions they came to. Another example having dozens of forms that look identical (user thinks 'ah another one of those' and feels comfort in that) Versus using a lot of variety in look between different parts of the UI so the user has a stronger feel of where they are in the hierarchy of UI.