nah, #1) autos life only takes 60-70 days from seed so you wouldnt want to shock them being that theres less time to rebound
#2) They sex and start flowering within the first two weeks (do you top your budding plants...no) more shock
#3) they are geneticlally made to flower quickly and effeciently BUT all the energy is supposed to be for one main cola- topping will gove you 2-4 colas and the plant will direct less energy at her main cola and will decrease your yield from your cola and the other branching stalks
4) under good circumstances ive seen them grow huge with no need to top or anything, mine are approaching 2ft
just some reasons y i wouldnt train them, check out my grow to see how they lookin