Depending on what sort of holes you are left with and how much space in the cavity there is, you could use some snaptoggles.
I have used these many times for larger items and kitchen units, nothing has ever gave way or collapsed, I agree attaching to a stud is the best way but not always possible and not everyone wants to rip off their plasterboard etc.
So so for a BM5 Toggler, Snaptoggle, drill the hole to 13mm and put in place, secure with an M5 Machine screw.