Laying out for someone is one of the most difficult thing to do in the pro shop only because it deals with customer service. One of the biggest things ive dealt with in my shop is explaining why with dual angles im giving them the same layout as bowler B but the layouts look different.
Speed plays a vital roll in pin placement, dealing with flare. For someone with a lower speed will have a longer pin to pap whereas the high speed will have a shorter pin. Matching up with the rev rate will also play a key factor. Someone with a high ball speed but revs to match will have bigger drill sums than someone without the revs to match. Same applies will lower ball speed. Obviously, low speed and high revs mean bigger drill sums and vice versa. The bigger problem is drilling for someone you've never seen bowl before.
To answer you scenario, with the 14 mph bowler, I'd go with no less than 5" (no more than 3" on asym) and depending on axis rotation and tilt would determine whether they need the ball to transition faster or slower and determine the angles. Same rules apply with the 19 mph bowler. You would generally go with a shorter pin to pap (or longer in the case of asyms) to get the ball to flare more and get the ball started sooner. And as applied above, rev rate, axis rotation, and tilt will determine the transition of the ball.
