The way you're wording it is really vague and hard to understand, but I'm going to take my best guess:
I would not break that skirt apart into sections if I were trimming it in bias. I would do it all in one go. If you're using double-fold, sew down the front side all the way around that over-skirt piece, cut and miter anywhere you need to, then sew the back side into place.
Although it's harder to miter inside corners, your seam would be a lot bulkier if you were to split the skirt into sections, bias-edge each individual section, and then sew them together. Also, if you're lining it, bias tape would be sandwiched over both layers as a finish.
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