I'm also an IFAA shooter and I do a lot of walkback from 10y to 80y, builds a very good sight picture memory of all the distances and make you hone your form. Start at 5-10 yards, take a shoot and move back a few yards after each shot, if you miss a shot go forward 5 yards and work baclwards again, what this does is allow you flow throough the easy distances and work more on the harder ditances.
Build your distance slowly over a period of time, if you extend the distance too far and too quickly you will lose confidence then form will start to fall apart.
Form and confidence is the key to distance shooting.