I've not done this very scientifically but below are a series of loaves with various slashes and proving times (AND proving methods - banneton, couche, retarded and not) to see how things turn out. The loaves are all baked at different times over the last couple of weeks. If I had the space and time, I'd do it all in one big bake-off.
Nevertheless, the results are vaguely interesting.
Loaf 1 - single slash lengthways.
Loaf 2 - triple and double slashes diagonally
The dough for these loaves was retarded over night. Not sure why some slashes remained intact and others seem to burst out.
Loaf 3 - triple slash diagonally
Again, one slash has burst like above. The crumb for this loaf however is tight and dry looking. I think I under proved the dough.