Hi,
it depends on the office, but the average turnover is 2/2.5 years.
Internally it is routine: almost every Friday a few colleagues send farewell e-mails to the office mailing list.
Bigger clients, who historically work with consultants, well know this aspect and do not care. In new small clients instead, middle managers can be firstly surprised, but McK carefully guarantees in the first period a continuity of manager or associate in the team.
Best,
Antonello