The Present Subjunctive or the Present Perfect Subjunctive is often used instead. This does seem out of character for French because it is a language that seems to pride itself on accuracy. So what happened? It could be because the endings are so long apart from the third person singular form. The other subjunctive tenses are nowhere near as long. Another reason could be because the Past Historic tense is only used in written French. As the Imperfect Subjunctive is based on the Past Historic forms this may have helped it to only be used in literary French.

A fun fact to know is with regular IR verbs the Present Subjunctive is exactly the same as the Imperfect Subjunctive apart from with the third person singular forms eg “que je finisse” in both cases.

I would say it is still important to recognise the French Imperfect Subjunctive in French literature and only to ever use it in written French if you are feeling incredibly brave!