Thats how I read it at first, but I think he is saying if someone has 2yrs experience then working another 2 years somewhere else would make that second job hal

Thats how I read it at first, but I think he is saying if someone has 2yrs experience then working another 2 years somewhere else would make that second job half of their current career. I think "work experience" would have been a better term to use.