I would like to share my experience and observations regarding this.

First of all, from what I know the local companies that offering this Trainee Drilling Engineer are UMW and Perisai. I'm came from one of them .

From my observation (local companies), yes, the training is to develop you to become a rig key personnel i.e. Driller, Toolpusher, OIM etc...Is it advisable? I would say yes because you will work as a regular roustabout, roughneck, etc etc....and will know well about the rig equipment and operations. First hand experience!

For some of the international drilling contractors (Transocean, Seadrill, Ensco, Diamond etc), they have different programs, either to develop management positions (rig manager, asset manager, subsea supt) or specific rig positions program (Driller, Subsea Engineer, Mechanic, ET etc)

In near future you want to switch to become drilling engineer (operating company/office job)? Yes I saw some of the trainees (international company) made that switch after a few years doing rig jobs (still in the program)...But, I never saw a guy completed his/her training and become a regular Assistant Driller or Driller switched to become Drilling Engineer. They already have fix rotation job with 4weeks on and 4weeks off (fully paid). Some of them that I see will progress up to become OIM or Rig Manager(office job) or another rotation jobs i.e Drilling Supervisor (operating company) or Directional Driller (services company).

So, for the start it is a good exposure and experience to start working hands-on in this trainee program if you are  good with physical jobs and know how to be good with people around you (friend/networking).

Later on, along the way the process you might have a better view or a better choices...