in progress vs on progress

Question

The expansion and definition of a brand is always, to a certain extent, work in progress. this example from Cambridge Dictionary

I want to know why 'on' cannot be used in the sentence.

In my opinion, 'Progress' means that 'Going to the aim', so that 'in' is more correct than 'on' because we cannot see obviously how the progress is going on at least in the sentence. To sum up, I think if we can see obviously how a work is going on, 'on progress' is more appropriate, but if we can't see obviously how a work is going on, 'in progress' is better.

Is my thinking correct?

Answer 1

(Posting as an answer because I don't have enough reputation for a comment).

@SIS, as a non native English speaker I totally understand that might not make sense. However, as in every language, you have your own way of writing and structuring things. Sometimes, if you analyse it, you think it doesn't make sense, but that's how language work, and at a certain point in my life I just had to start accepting that some things are written in that way. Period.

Remember also that in most languages, including of course English, you have "the rules", and but you also have "the exceptions".

I think the case of "in progress" is a mixture of all these issues.

You might want to have a look at this link.