USA head coach Eddie O'Sullivan revealed that the World Cup schedule was hard on the so-called minnows in New Zealand in September.
A series of battling defeats in the early matches gave way to increasingly one-sided scorelines as rugby's up-and-comers were repeatedly given only a few days' rest between games, while established nations played just once a week.
Tournament officials said the schedule was based on maximising TV revenues by allowing the best teams to play mainly at weekends, pointing out that millions of dollars were invested in minor nations' development.
But the controversy refused to die after outspoken Samoan centre Eliota Fuimaono-Sapolu compared the system to the "holocaust" and "apartheid", and several teams voiced their disapproval in less extreme terms.
"It does takes its toll, there's no question. It's a hard slog," said O'Sullivan, who experienced an easier draw when he guided Ireland in 2003 and 2007.
"When you get down to the back end of the pool games, a number of games in a short space of time, you pick up injuries, fatigue.
"All those games against tier ones (established teams) are real killers in terms of what they take out of the team physically and mentally, so I think we're beginning to see daylight appearing now in some other results."
The quarter-final draw is now made up exclusively of rugby's northern and southern hemisphere giants, despite a late charge by Pacific sides Tonga, who stunned France, and Samoa, who tested South Africa.
The International Rugby Board (IRB) released analysis after the first two rounds showing 'tier two' teams were catching up, with the points difference in their games against the big sides down to 29, from 42 in 2007.
But New Zealand, England, Australia, Ireland, South Africa and Wales then totted up a series of huge scores against struggling opposition.
James Robson, long-time doctor to Scotland and the British and Irish Lions, said teams needed a minimum of five days between games, but ideally between six and eight.
"I think to turnaround in international Test rugby now within four days is asking a great deal of the players that we are trying to care for," Robson said.
Samoa were particularly incensed when they had just three days off between their games against Namibia and Wales, against whom they then suffered their first ever World Cup defeat.
And Namibia's search for their first ever World Cup win was not aided by a punishing schedule of four games in 16 days.
"It's hard to play South Africa on Thursday and then have to play Wales on Monday. The turnaround was not suitable, not the most positive thing," said coach Johan Diergaardt, who returned to his day job after flying home.
However, Tonga rounded off the pool stages with a fabulous 19-14 win over France, while Samoa's fighting 13-5 defeat to South Africa was also a highlight although Fiji's campaign ended 66-0 at the hands of Wales.
France also had some nervy moments against both Japan and Canada, who impressed with some rugged displays as they beat Tonga and drew with the Japanese.
Japan's bid to be the "most improved side" was called into question as they yet again failed to win a game, extending a World Cup drought that stretches back to 1991.
And the former eastern bloc showed signs of things to come as Georgia beat Romania, and Russia scored tries against Italy, Ireland and Australia on their World Cup debut.