Did you see my example board in the “Replicate layout: Action plugin” thread linked above? That was done approximately in the way you describe, except that the repeated subcircuit is a hierachical sheet (which I recommend). Unfortunately the script by @MitjaN didn’t have all the required features back then. I will try the newer version of that script when I next time has similar need. Doing this thing manually is so and so bearable, but when you have to make modifications to the design it becomes extremely tedious. I just can’t recommend doing it manually if it can be avoided, not even with array and copypaste techniques.
In your tutorial you write:
This reveals that you didn’t read the mentioned thread. The script knows hierarchical sheets and knows which parts to duplicate. Traces etc. are also handled. In the thread I described how it could work a bit more intelligently and MitjaN implemented it.
You are right that
For simple needs your tutorial is good. But when you copy the tenth modification to ten subcircuits you will pray for a script. Otherwise, pray beforehand for getting it right the first time.