The thing with expo that most people don't understand at first is the higher percentage you use, the less sensitive the plane is around neutral. I always start with about 65% on ailerons. I fly a lot of planes with 45 degrees of aileron movement, but they are as easy to fly as a trainer unless I go over near full stick.

That being said, most beginners tend to out grow their trainers and unconsciously learn to put in full throw to get the roll rate they want. When they go to a more sensitive plane they can over control even though they use expo because full stick is still full stick. Look at the drawing Dave attached. The higher the expo percentage, the deeper the curve it, but it still gets to full travel at full stick.

It usually takes 3 to 6 flights to get used to a lot of control throw and expo. I twisted a buddy's arm for a year to get him to try it. Now he won't use anything else.