At Lehman Brothers, the waves came every few weeks.
On Tuesdays, HR fired business people, and engineering people cleaned up the mess.
On Wednesdays, HR fired engineering people.
On Thursdays, HR fired each other.
If you broke labor laws while laying yourself off, would it be grounds to sue the company afterward since the actions were taken by an employee of the company?
It's a funny thought, but I have to think it'd get noticed pretty quickly that you're suing the company for something you actually did, and it'd be dismissed pretty quickly.
It'd be fun to negotiate your own exit package in that situation though :-D
A few years ago I worked at a small-ish company that had to do a mass layoff of about 10% of their employees. The only HR person had to write her own layoff letter. A few days later she had to walk back her own layoff because the company realized they probably shouldn't layoff their only HR person during a mass layoff.
It allows you to ramp down without pandemonium.