Job hop after 4 years of work...?

I have been working in my current company for around 3 years. Although I have been working there for so long, I don't really interact with all my colleagues mainly because we do not work together or because I seldom see them in the office due to their frequent travels.

I was talking to my colleague whom I seldom really talk to when he was giving me a lift home. I do talk to him lah... Just not those in depth talk... He was telling me that it is time for a person to move on to a new area of work or a new company if they are doing the same job for 4 years.

He quoted me with an example that when his previous company was thinking of doing retrenchments, the consultants that they brought in first listed that the first group of people whom they should retrench are people who are above 45 years old and have been doing the same job for over 5 years. The second group of people whom they should look into retrenching are those who have been doing the same job for over 5 years. The reason being that these 2 groups of people are actually getting "expensive" for the job that they are doing as they are doing the same job and it is sort of getting "routined" to them. It does not bring much benefit to the company if they get their annual increment every year doing the same thing when the company will be able to hire new staff to do the same job at probably a lower pay.

I do recalled my lecturer in polytechnic telling me before that we should only stay on to our first job for only 3 to 4 years. If we stay too long there, we will be so comfortable of what we are doing that we will not want to leave our comfort zone. For me, I think likewise but I feel that it is also time for me to learn new things at another place. We do not need to change to another company, but we can look out for other openings in our company and work in another field.

I do not mind staying in my current company for long but I will want to work in another area. For me, I know that I do not want to stay in the laboratory forever. This is probably one of the reason that I took up my Advanced Diploma in Strategic Marketing in the first place. I do have plans to look into doing some marketing in the future but after I obtained my degree. For now, my current company will be able to provide me with an excellent environment for studying as I can leave my company on time. Now that my plans for studying may have to be shelved for sometime, maybe it's time for me to think of the future plans for my work...