Well I am flattered that you would repost my stuff...especially and give me credit
Starting with the pics...
So I think your new growth on all of them are looking healthy. I am fairly certain you are over the hump of the original problem and have things under control. I know for a fact the 2 bushy plants have rebounded. In general I think you can go as aggressive as you want on pruning at this point just remember never more than 1/3 of the plant in a week...and never do big pruning sessions back to back wait a few days between.
I am fairly certain the 2 that are slow are just over watered and need a good dry out. After a good dry spell and the next round of tea they will be banging.
As to soil mixing... (coco question is answered at the end of this but it is because of the soil mix so it all matters)
Well I started growing back before anyone would dream of having a website like this and talking openly on the internet about this stuff. Not to drag on but I did lots of experimentation and my good friend and eventual roommate was a horticulturalist. We worked on soil blends together for years. It wasn't until I started getting back into it a year and a half ago when I got on the web and found all these new ways of growing that were things I tried and discarded as inferior. I even got slammed on here back when I was just asking questions about it.
Anyway the point is I have tried lots of combinations of the basic parts in many ratios and many different flavors. But there are effectively 3 things to a good soil blend (not talking about a compost here).
1) You need a decent base bag of soil for a number of reasons. I have been using Fox Farm froggy lately. There are many kinds out there. I just grabbed the fox farms because it has on the label what I am looking for. I also found some real good stuff at Home depot. they are getting into it and have 2 real good brands there now so you don't have to go crazy at some hydro store. You want a soil that has Mycrorizal fungi, Oyster shells (or some kind of crustacean), Earthworm casting and or Bat Guano, Humic acid / humis soil / ancient forest soil (those are all the same thing basically...ancient forest soil is a very old greater than 100 year compost soil that beaks down into Humic acid). There are a few more things but if the soil you buy has that it will have the rest or at least is great stuff. Next time you buy a bag of good stuff look on the label and research the parts they are advertising so you know what you are using.
2) You need some straight up steer manure for 3 purposes. Mainly it is a huge source of nitrogen and done correctly is all you need for the grow. Nitrogen is the most commonly underfeed nute so have a ton of organic nitrogen in there is a huge help. Since it is poop and composted already it is full of all these microbes we keep talking about so you basically start right out of the gate with a living soil blend that is the bomb. And the third reason is you need organic material in there to absorb the nutes you add later. Without organic material fertilizers will just run out the bottom of the pot. They need to be absorbed into something and only organics can actually absorb and hold them. So with them you can feed less often and it acts as a very good time released nute provider but only in the proportions that the plant wants. It self regulates.
***NOTE*** Steer manure is not soil it is considered fertilizer.
3) You need an aeration component. You need something to make the blend light and fluffy and full of air. Perlite is great for this and also has the added benefit of retaining moisture well.
So the question is why coco...
Well Coco works as both an aeration component and an organic component to retain fertilizer. It is used most commonly in soilless mixes for these reasons. But the main reason I tell people to use it is newbs freak over a little nute burn.
I honestly mostly have used the first 3 components exclusively in a 1/3, 1/3, 1/3 ratio for many years. But you have to deal with slight burn in early veg as it is hot. But you get real great performance for a long time without any fertilizers so I put up with it. Now if you do the math there you notice that I am 2/3rds soilless. At that ratio you get all the benefits of soil and soilless. You get nearly hydro growth with tempered pH control, great organic performance with natural beneficial microbes and long term slow release natural balancing nutes.
So lately I have been recommending to people to cut down the manure a bit replace that with coco fiber to compensate and keep the ratio of soil the same. You are adding in useless organic matter by adding the coco which is basically replacing half of the manure. So you get all the same stuff just a reduced nitrogen content so less burn.
I came to 1/3, 1/3, 1/3 after tons of experimentation with many types of amendments and ratios. I tried all sorts of things and as most things in life the simple answer is the best.
Now if you go to using a compost at the bottom of the pot like Subcools you can nix the manure and go 1/3 coco as there should be enough in your soil portion to get you through until you get to the compost but I like to keep it in there at the ratio of 1/6 like I stated.
So yeah that's what coco is for.