On Friday, 1 February 2019 17:15:09 UTC, R D S wrote:
I got a 2 gang surface mount back box the other day that had cable grips
in it, which I thought was a good idea.
But it only had two, and they weren't opposite but one on the side and
the other top (or bottom).
Has anyone any idea why this would be? Why not fit them on all four sides?

For a cooker switch with an outlet cable, probably. Cable grips take up space, and cost the manufacturer money, so they don't fit four. Only one will be likely to be required.

Owain