I use a handful of number formats as personal standards. Is there a way to make them “favorite” or “preferred” in Calc so that I can navigate to them more easily than paging through a long list of formats that I mostly never use?
No there is no way - the preferred method is to use cells styles for that (which in turn could be defined for a customized default template).
And I suppose there’s no way to use a customized default template for spreadsheets created by importing from CSV? That’s when I’d like to use it most often.
I just found the answer myself: How do I make Calc use my default template?