Huh? What in the description makes you think that the effects should stack? A ship can only have one crew, how would they take three simultaneous training courses? A planet can have multiple climate control or value improvement plants, sure. A planet or its atmosphere is very large and there can be cumulative effects. There is no logical way I can think of that training should have a multiplying effect. I really expect that something will be changed to prevent this now that you have pointed it out.