Does "-ing" always tell us about duration?

Question

I saw two sentences in one of threads:
(1) Having finished our work, we went home.
(2) After finishing our work, we went home.

I have a question which was perhaps already answered in that thread but I couldn't understand it.

As far as I know, "-ing" always tells us about duration, i.e. when we want to emphasize an action doesn't happen immediately. But translating (1) and (2) into my native language, I can convey this sense only in (2) but not in (1). For this reason, could you please make it more clear to me:

Is it correct that in (1) "having finished" denotes that the process of finishing took some time?
Is it correct that in (2) "finishing" denotes that the process of finishing took some time?

Answer 1

It is not true that "ing" always conveys duration.

Your example sentences have similar enough meaning, and neither one conveys duration.

"Having finished" means because we had finished.
"After finishing" means after we had finished.

Again, no meaning of duration.

Further, the meaning of "finish" in that context is an instant event, marking the line between working and not working, so no duration is possible. Both sentences describe a simple sequence of events: work ends, go home.