“LIFELONG learning” is a phrase beloved by business schools. But not, it seems, by their clients. According to a recent survey by Mannaz, a management-development firm, the number of professionals taking part in formal corporate training drops rapidly after the age of 55. Are these wise, old heads being overlooked?It is tempting to conclude that older executives are falling victim to age discrimination, as firms focus resources on younger talent. But according to Jorgen Thorsell, Mannaz’s vice-president, this is not the case. Reticence, he says, comes not from the organisations but from the employees themselves.Mr Thorsell believes that conventional training simply no longer serves their needs. Formal programmes are often seen as a repetition of lessons already learned and become increasingly irrelevant in the light of experience and expertise. The resulting “training fatigue” is resistant to most incentives.This doesn’t mean that more seasoned executives have completely abandoned the idea of personal and career development, however. Instead Mr Thorsell says that this group prefers a do-it-yourself approach, conducting their own research and swapping war stories with their peers rather than take a place at business school.