My own experience. With irons it's not so critical to try to hit from the inside. It happens by itself almost automatically because irons have a more vertical angle of attack.
With woods and driver, given a more horizontal angle of attack, if you don't make an effort to hit from the inside it's very easy to come out of plane and hit bad shots.
Hands too low, stance too open, knees flexed too much, etc.
I'm no expert but I have read that most people fall between two degrees upright to two degrees flat AT MOST. Very few people need three degrees upright or three degrees flat.
My personal view based on my own experience:
practice is good if you know what the problem is and how to fix it.
If you're not sure what your problem is it is much better toget lessons first.
If you think you know what you need to do and practice a lot but you don't improve then it is very likely you have your problem misdiagnosed and you should get lessons.
I first wrap the shaft (label part) with a piece of cloth or my handkerchief and rub back and forth vigorously. The friction does a pretty good job of heating the shaft and the label and then you can peel it off. Any residue can be removed with goo gone.