There is no point in having a 90 notice period clause since as per my experience, it is very difficult to implement. In any case, an employee who has put in his papers and made up his mind on quitting the current employer, becomes mentally and emotionally disengaged. Hence, even in a handful of cases where such employees do serve the full length of the 90 days notice period, they typically do so with a disengaged frame of mind which can be risky and their productivity during this phase is questionable. Further, efforts to force exiting employees to serve the full 90 days notice period only generate ill-will which can be destructive to the moral of your talentforce.
In one of the organizations that I worked for, we had a 90 days notice period clause. I took upon myself the self-initiative of analyzing the historical data since the 90 days notice period clause had been introduced (prior to this, the company had a 30 days notice period clause). I found through my analysis that typically, employees who had joined on a 30 days notice period contract, had twice the tenure of those who had joined on a 90 days notice period (after adjusting for the fact that typically those on a 30 days notice period currently would have joined earlier than those on 90 days notice period clause). I also found that most of the attrition for those to which the 90 days notice period clause was applicable were moving away prior to the completion of their probation period since prior to confirmation in employment, the 30 days notice period clause was applicable. Based on this analysis, I recommended a change back to 30 days notice period on either side and the strenght of this analysis had the management accept the practice of bringing back the 30 days notice period back into force.
The point I am trying to make here is that such things as 90 days notice period clause destroy the psychological contract that the employee and employer share with each other and come across as being arbitrary and favoring the employer. They end up doing more harm than good.
Thanks,
Snoopypryer.