Good morning Emeraldo, beautiful plant . I plan to grow 2 land race sativa s indoors after the new year.Topping 6 all at once might slow her down, but prolly no harm done. I have a three-tipped plant in this grow, the Durban that at first could not put out a leading growth tip, so she put out three with equal vigor and dominance -- they are all three growing at the same rate.
I was thinking of topping all three, but it might be easier on her if I topped one each few days or so. Thing is, the grow experts say topping should stop two weeks before flowering starts, so I'll need to have all topping done by about August 1 or so. Topping or FIM maybe would be better than topping.
Maybe @Stunger has a comment on that. I have the impression he is more into LST than topping, though quadlining starts out with some pretty massive topping. I'd just prefer to chop once or twice.
The Dos si Dos i'm growing has 6 dominant yet fairly equal mains with 4 others that are also similar. My plan is to top the 6. I'll probably do the 4 uppermost nodes first and wait a week before topping the last. I do want to slow the upward growth down as I am concerned with greenhouse height. Pic for reference.
I admire your grows. Take care