Renewal (tajaddud) refers to an act taking place repeatedly or afresh, while continuity (istimrār) refers to an action or state continuing for a period. They are distinct, though a present-form verb can suggest either when the context permits.
“يَزُورُنَا الطَّالِبُ كُلَّ جُمُعَةٍ”
“The student visits us every Friday.”
“كُلَّ جُمُعَةٍ” indicates recurring occurrence.
“يَنْتَظِرُ الرَّجُلُ مُنْذُ الصَّبَاحِ”
“The man has been waiting since morning.”
“مُنْذُ الصَّبَاحِ” makes ongoing duration prominent.
The present form does not universally entail uninterrupted permanence; surrounding expressions narrow the intended temporal meaning.