Models have different variables in them, I'm wondering if what variables work for one year work well for next year. I personally use different percentage weightings for all my variables. For those that do the same, how do they differ from year to year if you tweak them for each year? Example I use variables X Y Z, at 33.33% each. Now pretend it worked well last season, will a new season maybe have to be changed to 40-20-40% to work best? How dramatic a change should I anticipate year over year?