As per instructions, I made a dry spicy rub which I coated the blade roast
with and let sit in the fridge overnight. Seared the roast for a couple of
minutes on each side, then removed from heat. Fried up some onions and
celery, added a little bit of red wine, brown sugar and garlic. Put them in
a roasting pan below the roast. Cooking at 300 degrees, this was supposed
to be ready in 3 hours.

It's now been 4 hours - the roast is tough, tough, tough. Now if I kept it
in for another 3 hours or even perhaps turn the oven off and leave overnight
will it become more tender?

Elaine (whose supper plans are now meat pies).