In their primary conditional use, in and idha make the response dependent on the occurrence of a future condition. This does not require the outward verbs to be imperfect in every sentence.
Example 1: «إِنْ تَجْتَهِدْ تَنْجَحْ» — If you work hard, you will succeed.
Example 2: «إِنْ اجْتَهَدْتَ نَجَحْتَ» — If you work hard, you will succeed.
The second uses past forms, yet in the context of an upcoming examination both occurrences are projected into the future. Grammatical form and event time must be interpreted together with context.