You would trim for a #7 wood since the #7 wood head weight is heavier. How much more you trim does depend o the shaft and what the original trimming was. As Rlafoone stated, depends on what the shaft was to start with and how it was trimmed, as well as how much parallel tip length is remaining. Some shafts may not have any additional trimming after a #3 wood or a #5 wood based on the parallel tip section length. And, some shafts are butt trim only, as Rlafoone stated, with no tip trimming at all.