Helizamba, pilot crewing is mandated legally, just like pilots duty times.
Engineer/Mechanic crewing levels are not legally mandated so companies will go for the cheapest possible option they can get away with. If they could have one licensed Mechanic for every 100 unlicensed, then they would.
Same for duty times for Mechanics, there is no such thing legally. If the company wants to work their Mechanics for 12 hours a day 7 days a week, there is no law stopping them.
Have a look at some of the biggest offshore helicopter companies in the world. You'll see that pilots must have 1 day off per week plus one day off after a night on standby.
Their ground based counterparts (unless stipulated otherwise by the oil company) get zero days off per week and after a night on standby, are expected to be at work in the morning to continue working. Contracts are crewed, ground crew wise, with NO allowance for days off/sick days at all.
Companies around the world are fighting to stop changes being made as they say it is financially not viable to operate if Mechanics have duty times and rostered days off.....