Having the benefit of flying for a number of operators in my career I think that I have probably experienced the whole spectrum of training/currency requirements. The major operators seem to have the best initial and recurrent training systems but these are also the pilots who are probably getting the most regular exposure to flying. An average in my experience would be 5-600 flying hours per year offshore and 2-300 hours SAR/EMS.
I have also worked the VVIP circuit flying for seriously wealthy people and the average was maybe 50-100 hours per year with only the 6 monthly OPC to maintain any kind of currency. Although the initial hiring qualifications were high there were minimal flying or recurrency requirements. Certainly nowhere near comparable to non-VIP operations. The expectation was that not having flown at all for maybe 6 weeks I could depart from the deck of a super yacht over water at night single pilot and get these people to wherever they wanted to go with little notice - or my employer would be told I was 'not suitable'.
Not all owners are so ignorant of course and I now work for one who understand the correlation between currency and safety. I was offered a job with the Haughey 139 operation but turned it down as I knew that I would not last long there.