I would. YYZ-YVR is 2085 Miles. Assuming 10 minutes of taxiing on both ends, that leaves you 4 hours to travel the distance or 521 mph average speed. That is also assuming that you take off to the west in YYZ and land to the west in YVR. If you need to turn, you will have less than 4 hours. The crusing speed of a 737 is 583 mph. This is not achieved for the whole flight since you must climb and descend. The average speed is probably closer to the 521 mph. Westbound flights must also fight a headwind, reducing their average speed further. I believe the published block times of 4:50 to 5:15 are more accurate compared to the 4:23 that you quoted.