With FROV (not FSL anymore, they are purely survey, ROVvers moved to F Rovtech when they bought them) there are a couple of different contract options but you get your salary all year round whether you work or not.
If you attend a training course, these days do not count towards your contracted number of days but you still get your salary plus an onshore allowance for the day. Basically just the same as working in base but the day doesnt count towards your 170 days.
The structure (from bottom up) is Trainee, PT4, PT3, PT2, PT1.
Very generally, Trainee is 0-6 months, and then PT4 and up to PT1 within 3 years.
Whether you call a PT4 a cheat way of putting a Trainee offshore depends on your definition of a Trainee. People at "trainees" at every stage in their jobs. By PT4 you will have done the training, HOPEFULLY already have a trqde behind you (a different debate), plus have done 2 or 3 jobs already offshore. If you have all of this then I feel it is reasonable to put a PT4 out on a team – DEPENDING on the job of course (simple drillsupport, small stuff and built them up to heavy, more manic jobs otherwise it is not fair on the team or the individual).
Problem is getting the right balance, put them on too easy a job – they learn nothing. Keep them on easy jobs, they do 2 years offshore, everyone thinks "oh hes done it for 2 years", stick them on a manic job and everyone suffers.
Its all about managing, balancing and developing – some companies are better than others 🙂