Is it a practical goal to make short notes of classical commentaries (Seervai , Ramaiya , and so on ) ? How much time would it take ?

Is is not practical at all but a mere foolish attempt. It would take atleast 6-7 months to complete all the volumes of even one of them.

Why?

They are classical commentaries for a reason, not a dukki.

ChatGPT, summarise this for me.

Concise books are supposed to be short notes of sorts, of these larger commentaries. If you want something to look through quickly, say before an exam, a concise would be better. If you wanted to gain clarity on a niche issue, a commentary would be better. I don't think it's very practical (or helpful) to summarize commentaries, except perhaps that you might remember it better if you make short notes

Thanks