This has not been my experience. In my case the staff is eager to stay on because they think they will gather skills. Yes you do lose them a year or two later to attrition because they land better jobs with their improved skills - but you get a year or two of fairly decent work out of them. I consider that a fair trade in terms of time - one week of my time to get one / two year of good work from a team of 8-10 people.