I remember something USATT Hall of Famer Ricky Seemiller once told me at one of my first training camps: "Amateurs practice to the middle forehand and middle backhand. Top players practice to the wide angles." What does that mean? Many players get in the habit of warming up and practicing their shots to exactly what Ricky said - the middle of their partner's forehand or backhand sides, rather than the corner. Watch them warm up forehand to forehand or backhand to backhand, and you'll see their shots, on average, are 6-12 inches inside the corner.
What you practice in practice you will do in games.
Top players don't generally practice or play to this area - why would they make things easy for their opponents? Even when warming up with simple forehand to forehand or backhand to backhand, their shots will average right over the corners, going wider than the corners about as often as inside the corners. Do the math - it means opponents have 1-2 feet more table to cover, but more like 2-3 feet since shots to the corners are usually crosscourt and angling away. That's a lot of table in a fast-paced game like ours.
I'll say it again: What you practice in practice you will do in games.
So, next time you warm up or practice, focus on keeping your shots to the forehand or backhand to the wide forehand and wide backhand. With a few exceptions, essentially every shot you ever do should go one of three spots - wide forehand, wide backhand, and the opponent's middle (the transition between forehand and backhand, usually around the playing elbow). Since those are the places you should be playing at, those are the places you should be going to when warming up or practicing.
I'll say it one more time: What you practice in practice you will do in games.