Is it proper for a marketer to work for one employer for over 5 yrs? Is is good to move on to a new employer? What can be the advantages/ disadvantage

Focus on one business more than5 years has advantages and disadvantages and advantages of avoiding the mistakes of marketing more than once with the knowledge of the extent of the impact of the marketing campaign for the product in terms of interest and knowledge of style consumer for this product and also take advantage of the experience gained from the job and use it in other jobs

There is an advantage and disadvantage as others have said, be sure that as much as you stay in the same place then you would benefit more experience in that particular place also the work procedure would be familiar to you and there is a big chance to be promoted to a higher postion since you are one of the experts.
But again, sometimes the personal needs or some other attractive job offers or kind of challenge, would encourage you to change your work.
So it has nothing to do with '' TIME '' whether5,3 or10 ..
it is about the person himself and his decision based on so many factors and needs.
Regards,