It's very strain dependent. No topping (at least I've never seen it). The only thing I've seen people do to it is cut off weak branches.
It can be perpetual, but it's usually done in batches. It looks more like this...
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The reason I bring it up is bc you seem to have a lot of wasted space in that area. & that's fine, it's your grow, your prerogative.
But if you were to grow like this, it would make a better use of your space. Scrogging is great for high yields & big plants, but it's a pita to work around in my opinion. I did it once, & haven't done it again because I hated working around it.
The above pic is hydro, but you can do it in soil. So basically, you would have space for say 32 plants? You can either do ph by adding one plant at a time. Or perpetual harvest in batches of 32.
Some people say the latter is not ph. I say it is. What is the difference between someone vegging out a plant for a while, so you have 32 tops,outputting it in the flower tent, vs. having a batch of small plants with 32 tops & doing the same thing? Nothing, that I can surmise.