Very small briskets......depending on what temp you cook them, but I'd think if you cook them at 275 they should be done in about 5 hours +/-. No guarantee on the moist meat being that small. I normally cook whole briskets that are "about" 10 pounds and they take about 12 hours at "about" 235 degrees +/-.
If your "Butcher" cut the brisket in half, you will have a fat end and a lean end. The fat gives it tenderness so you may end up with two seperate meats tasting different.
Good luck however.