At my current level of competence in printing, I need all the test strips I can get! So I trim my paper first and save the offcuts. 11 x 14 Ilford Warmtone is expensive experimenting, so usually I cut the offcut into two or three pieces and test on what my eyes tell me are critical spots before risking a full sheet.

Like wfe, I don't experience much trouble composing to the frame, whatever it is, and I generally (but not always) print with minimal cropping.