when drawing molecular shapes, how do you decide which atoms go on axial or equtorial? (the more electronegative goes on _____)

please help, my textbook confuses me with exmaples that follow both sides!

The only example which I could find that would make a difference was in this reference below. It shows many types but scroll down to trigonal bipyramidal (PCl3F2). The F atoms are in axial and the Cl are in equatorial.

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