I agree, if you're not pressed for time mainlining is worth it. It's fairly straightforward and easy to do as well. If you're worried about being able to safely top and split let it grow an extra node or two and cut it down a bit further so the stem is a bit sturdier, eventually you'll be topping them while the new growth is tiny to save a bit of veg time. I think I cut roughly a week off of my veg when I got more confident on working with smaller stems. I don't specifically manifold/mainline anymore but I definitely follow the same general idea of making a nice flat canopy before flipping. These were some potential mothers that I decided to flower after picking my best this go around.
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Just remember the exact way you train usually doesn't matter so long as you use 100% of the area of your lights footprint. Filling your area and light are the two biggest factors of yield in my experience, nutrients are pretty minor in comparison to environment. I used to be in the headspace that having a full line from AN/Canna/whatever "Best nutrients available" with all sorts of additives was the way to go. Now I veg with just my soil amendments, tea and kelp/fish emulsion, and bloom with 1 pk booster, and a couple of other products that I liked over the years. Less is more is generally a good mantra. The only exception yo that is pest control. Always better to be safe then sorry, just do your research on what you're using. A lot of people will recommend commercial pesticides that aren't necessarily safe for indoors, or for a product you smoke.