Twisters don't do large numbers of cross overs during the regular season, they try to keep them to a minimum. So it wouldn't really fit their gym's approach to have Weather Girls be full year right now. I think they are dedicated to developing this group of girls on Juniors and SO5, so that they are fully ready to move onto teams like Reign and F5. Weather Girls is more of a bonus at the end of the year to try and give these girls a worlds experience. So while you are correct they would probably do better at worlds if they were full year, they might miss out on some of the age appropriate and developmental benefits that Jrs and SO5 provide them. So having Weather Girls as a half year team is a win-win for the kids, regardless of whether or not they globe at worlds. (p.s. these are my observations, if I have misrepresented the gyms intentions, a current gym member can please correct me)