Toronto to Montreal is 5 hours if you don't stop and average 120km/hour. At most 5.5 hours.

Toronto to Hamilton is 45-50 minutes.

Of course everything depends on traffic. I've done TO-Mtl in 4.5 hours. But if you leave at 5pm on a Friday from Toronto to go to Hamilton and there is construction it might take 1:15-1:30.

But who ever said 7.5-8 hours to go from Mtl to Hamilton is definitely not from the anywhere near the area.