I am somewhat of an aiming system geek, 90-90, center to edge, poolology, shishkabob, all produce a consistent angle when executed correctly, shadows and lights can produce good results provided the table is lit correctly, many bar tables are not. I did find an aiming system that finally checks many boxes for me and when executed correctly it is very accurate and produces reliable repeatable results. Where you ask did I find this marvelous system, on a snooker channel on you tube, thought the balls are a different size they are still balls, The gentleman on this site has some great ideas that can carry over to pool, I have included a link to his aiming system ttps://www.youtube.com/watch?v=Q5b34KXNzNg it's titled what is the trick to snooker aiming he has many other great videos on aiming as well.