this has been bugging me for some time. I feel that it is necessary to repeat the pronoun after using a conjunction where a different verb, or at least a different instance of the verb is being used. However, many people I work with seem to disagree. By way of illustration:
1. He is a conscientious character and is developing well in his trade.
2. He is a conscientious character and he is developing well in his trade.
I suspect that example 1 is a more colloquial, spoken register but that example 2 is more appropriate for a formal, written use.