I have a swag of cracks to repair at home where there has been movement in the building. these are all butt joints where there is probably no backboard. I have added a few extra screws here and there and am now ready to redo the joins. I read online somewhere that its best to remove all plaster and tape around the crack, essentially returning the join to its original form (before plastering). Is that the case? it seems logical to me to do it that way but just thought i would check here. secondly, what jointing compound(s) should i be using?