If you draw straight lines on a table (corner to corner both ways for instance) do they provide a crutch that is not available if you play on another table? Said another way, if you use the lines to judge your straight in shots, does your alignment suffer if you don't have the lines. I have seen a few instructional videos where the guy has drawn straight lines on the table for practice, but don't want to use a crutch if will hurt my game in the long run. Any thoughts?