When you say more volatile, you mean teaching at poly is more unstable and the contract may not be renew? Or do you mean the job scope is volatile meaning, high variation in things you do? I thought a teaching job in poly will be more stable than a normal job and is something you can do till retirement?

Picking back the knowledge and the teaching skills will be tough in the 1st year for sure as it has been many years since university.

Private manufacturing companies are in the constant change of moving jobs in/out of Singapore subjected to cyclical demands and adjusting the size of workforce according to business needs. If you not in Director / HOD Positions, you may have trouble finding Engineer and manager level job from 40 to 45 years old onwards if you are given the golden handshake or have to quit your job for whatever unforeseeable reasons. Reason being younger guys can do your job cheaper, better and faster. Not sure how many ppl agree with me but from experience, I have ex principle engineers/Managers applying for Snr Engineer job and I just couldn’t hire them due to higher pay and also fear of them moving on to any companies that willing to give them more.