So once during an Environment art lecture, I had accidentally pressed ctrl + 1
and it had created my walls more detailed (because of adding more polygons)
at that time I didn’t know it was the shortcut to the same modifier as shown in this
topic’s lecture. I asked the question because is it a quick shortcut to do it or
do I need to be aware of certain values that get automatically set with the shortcut
instead of doing it manually via add modifiers ?
It is just a shortcut. It will add the subdivision modifier in its default mode.
It is the strength of Blender, having shortcuts. But you need to know them.
There are many, but are some (be aware that shortcuts only work in certain pannels, there where the mouse pointer is. A shortcut in one pannel can be different in a other context).