I am fitting a new desk top for younger son's study. I needed to allow computer cables to go from underneath to the desk top and vice versa. I had just spend several days sanding and sealing the slab of pine and didn't want to cut a hole in it. The slab butts against a stud wall. Musing (as one does) I realised that a double cavity wall socket box set in the plasterboard, with the longest side vertical, and equally above and below, would have room for several cables. I'll trim a blanking plate to seal off the hole.
Just thought I'd share that with you...