If you're not making mistakes when you are practicing then you aren't challenging yourself.
Team shooting drill. 80 makes in 8 minutes. Mid range, baseline, elbows both ends of the court. 1 line, 1 ball. Harder than it sounds!
Hard 20 minutes at game speed or high is better than 2 hours cruising and chatting.
Attitude goes hand in hand with talent. You need both, not one more than the other to be successful.