Yeah i do it some times, you know when you have to, due to lack of materials, but i would not recomend it, did a job many moons ago hardwalled a wall around a door as it was too thick to just to skim on plasterboard and the whole lot litterally fell off and had to redo it with bonding i think the door vibration opening and closing had something to do with it. But its like the M R board you are supposed to thistle bond-it before you skim it, dont happen very often on site usually pva it and skim never had any probs with that, but a mate of mine said he had a whole ceiling fall down and he wont touch it with out the bond-it.