The alternator is one of those parts that are not unduly affected by driving "style" - it will work for a long time typically, probably never having winding failure, if not electrically abused. What is bound to fail eventually are the brushes and the bearings but these are both preventable occurences with good maintenance (see my other post - well, nobody's perfect, I just didn't get round to it!!). The unforseen potential failures are the rectifier and regulator - both semiconductor devices operating under hostile conditions. Recommendation then is to change the brushes and regulator (both cheap and accessible) before it's too late (like I didn't!)and, providing the rectifier keeps working, you should be fine. Hope this helps.
BillB.