for years I've used the 3 4 5 method , but for the quickness you cant beat the laser square ,my mate as the gtl3 cant fault it on the small to med size jobs, did struggle seeing the line on a big job we've done , I went for the ptl ft 90 which i also cant fault ,had 2 cheap ones as well ,both worked spot on first 1 was a Stanley ,then I picked 1 up from lidl for less than tenner ,