I'm not fond of big nested menus in general either, but they are good for quick exploration and can be pretty forgiving of poor categorization.

I do wonder if sometimes the nested nav is too in-between. Maybe the solution is not to try to squeeze it all into that structure but make "finding the page I want" to be a more top-level experience. EG don't take me to a Category Page, but do let me select a category and start drilling down, whilst keeping it easy to switch between top level categories.

Big nested navs are often just ... fiddly.