On plasterboard wall I have a hairline crack (settling) I scraped it out to form a channel roughly 4mm wide and 3 mm deep (about 2 feet long) I filled with filler but have noticed after a couple of days the edges are showing a hairline (presumably) shrinkage crack. Should I just go over this with some more filler and then smooth or better to get a flexi filler, or something else.
I just used a cheap filler I aready had.