For training, I tend to recommend just topping. Put a lot of plants in a small area and go for height. Deep canopy penetration. If you defoliate well with this you'd hit stupid yields and you don't waste time training plants with LST and Mainlining.
LST and Mainlining are fun don't get me wrong - it's how I started. But after a couple of grows, it becomes so tedious. Also, IMO mainlining sets your plants back a couple of weeks. I've done side by sides (two weeks extra veg on the mainline vs just LST) and yields were around 5g's more which is pretty marginal. Of course, this is not a comprehensive study but I've heard similar stuff on forums so I'm leaning towards that outcome.