I believe the incidence of FDA withdrawal of a widely used drug is very low. There will also be incidences of side effects and incorrect usage of the product. This is the reason why the sales person is so important to impart the proper usage of the product, including the contraindications. They probably would have invested several years understanding the therapeutic field they are working in and cultivating doctor customers. Doctor customers would probably become friends and hence visiting customers will be like visiting friends daily.
Work becomes easier as their competence level increases.
Their worth to their company will have gone up a lot and correspondingly their pay package. By this time they would have the opportunity to be promoted to sales manager, marketing manager, divisional manager and even with regional responsibility. He has to spend more time educating the healthcare professionals. Often companies use group seminars where a leading doctor trains other doctors on the products, delivering scientific papers. The sales rep would then follow up in the doctor's clinic and answer any questions.