Gerrit said: "Plugins are a great way to level up SketchUp."
They are. But I feel there is more sense in pressing the SU developers to better the bare SU body in terms of efficiency, functionality, stability and overall performance than sitting and expecting people to spend their own time in making great plugins. After all, it's their program. π
One more word about plugins. I remember that once (in one day precisely) I downloaded I huge bunch of free plugins. As Jean pointed very well, that's the situation when the SU interface does look like CATIA (if most of them are visible of course). But no matter how many plugins you have it seems to me that SU always starts much faster than those monster programs with million functions and several GB in size.
After trying them I deleted the most since I realized there are some that repeat some functions of other plugins and some other perform the same function with more reliability and speed. At the moment there are, I think, several plugins with 'make roof' function. Over the same base (face) some of them need one second to produce a desired roof and some of them ask several seconds for the same action and result.
I guess it all has to do with the algorithm applied. And you were totally right when you mentioned knowledge needed for this kind of work. And bright mind, I'd add. π
It was a pleasure having you here again, Gerrit. Come around any time. π