theres a bunch of different factors. a big one that people tend to overlook or not understand is boot sole size. If you have a smaller boot you need to add to your setting, a larger boot you take away on the chart. This is because more force is needed to release a small area, whereas when you have a huge clunking boot you can have minimal pressure but a big amount of leverage due to the size. This should all be done by your shop according to the info that you give them, and then if you feel your pre releasing or vice-versa then adjust .5 at a time. I usually end up going 1 full number above what the shop has me set at, some people ride less than the shop sets them at.