How about this one? When you are faced with a bit of a monster hole and one box of polyfilla just won’t do the job, how about packing the hole out with crunched up tin foil. Bed it down well into the hole and skim over with filler to finish – easy one!
I remember a big hole in a wall behind the door, the filler just slumped out each time I tried to fill it, using this trick would have saved hours and much profanity…..