I do partially agree with
@Organoman but I believe that it all depends on several things. You're definitely able to top, defoliate and train the shit out feminized and automatic plants. The question is, is you environment perfects, is your medium in perfect condition, are the nutrients on point, the DLI and are you experienced enough to know when enough is enough. I've had great success with all the training methods on automatic plants but I've also "failed" on some. I'd suggest that you top and train genetics that you definitely grew before and know for sure that they can handle it. If you grow new genetics you'll never be able to fully know if the plant can handle defoliations, toppings and stuff, but you definitely CAN do it. For less experienced growers or if you know that all of the above are not on point, I'd say to leave it alone and just make them as happy as possible.
XOXO
Cremo