In big companies here, regular employees are prohibited to engage in another job particularly if the job is related to his wok in the company. The rationale is to maintain good focus in the work and to have a solid loyalty to the employer. But sometimes employees would venture into other part-time jobs to augment their income. And when the company discovers his violation then he may get terminated. I had a colleague who was doing extra work outside. Making the situation worse is that he would come to the office for just a few hours then leave for his other job. He is a supervisor so his attendance is up to his honesty – and he was so dishonest. What is your opinion on the prohibition of doing extra work for another employer?