A few things I haven't seen discussed on this thread.

1 The insurance companies are very good at assessing their level of risk exposure and approriate compensation for those risks. As pilots that may not have ever had to pay for the insurance on an airplane, many folks may not be aware that the folks with less than 1,000 hours pay a much higher rate then those above. Does this mean a person with 998 hours is more likely to have an accident than a person with 1,002 hours... no, not specifically. The insurance companies have taken the accident and claims paid in comparison to flight hours and determined the magic numbers are 100, 500 & 1000. The highest accident/incident claim/loss comes with the 100 hour pilot, the second most claim prone is the less than 500 hour pilot, and the least accident/incident prone was the over 1,000 hour pilot. The exact formula they use is a mystery to me, but that is how they have chosen to price their premiums for aircraft owners.

2 A review of the anual Nall Report, available free on AOPA online, will support the insurance industries claims of the 100, 500 & 1,000 hour breakdowns.

3 While nobody is saying that endlessly droning around in a 150 around the local practice area is a good experience as 1/3 the time practicing and flying IFR... what people are failing to acknowledge is the fact that the longer you spend time in airplanes, the greater the opportunity to have had something go wrong inflight, requiring you the pilot, to make very important decisions.
Many people experience their first emergency and leave flying all together.... most airline pilots have experienced several emergencies, or critical situations, BEFORE they ever stepped foot into a part 121 airline flightdeck...
An informal conversation with a few of your company check airman who do IOE will undoubtedly reveal many of the newer lower time pilots who have "frozen up" when a master caution or master warning tripped... it isn't anythig against them, they just have never been in an airplane when things went rapidly south. Comming from a college or bridge program with state of the art equipment that you have flown for 250-400 hours without ever having so much as a hiccup doesn't afford a novice pilot the opportunity to have dealt with a critical event.... if you fly long enough, everybody will get their chance... most have had the chance when they were only risking their own life... now we do it with passengers.

just a slightly different take on the subject.

.02