I used to play in an 8 ball league that played 1 rail bank on the 8 or 3 rail kick at the 8. I got pretty good at the spot on the wall thing. Most "venues" we played at it was pretty tough to be able to use a consistent distance for your "spot on the wall". I would start by checking the table by using a spot on the rail then I would move that spot from the rail to something behind it, a wall, a table, juke box, etc, hopefully something that wouldn't be moved throughout the night. Using 1 tip high and 1 tip inside i was able to make these shots very consistently from different starting locations, even moving the object ball up to a diamond a long either rail, beyond that and it got pretty tough. I always tried to use a point that was around at least a table and a half away, I didnt want anything too close or too far and that seemed like a pretty easy distance to obtain especailly if the "venue" had multiple tables.