Since the OP was specifically about layoffs, I’ll confine my comments to those (I’ve been the manager responsible for more firings than I like to think about, but those are another topic).
In one case, where I was essentially running a company that was the only going concern among several shells owned by a holding company, when the parent decided to get out of the business we were in, I was asked to help arrange for a buyer for the intellectual property. I did so, and once the deal was agreed to, I met privately with each of the remaining employees to explain that we would be wrapping up operations as of a particular date, that they were welcome to remain at work until that time, and that I would do whatever I could to help them with the transition. For one of the support people, I also worked out a deal with the acquiring company so that she could continue to work providing support to customers (since they had no one with the relevant experience) for a certain time after the deal closed. Most found other employment by the final day, as did I – I got on a plane on Thursday night, delivered the hard drives containing all of the relevant information (source code, manuals, marketing material, etc.) to the buyer on Friday, flew home that night, and started a new job on Monday morning.
The next time I was involved in a layoff, it was on the other side of the table – I was working for a California-based company, but working from home in Atlanta. We’d been through one round of layoffs a couple of months before, and knew that there were more coming. The project I was responsible for was designed to provide infrastructure for growth that had not materialized, so I knew the end was near. Because I was a remote employee they didn’t have to do much beyond cutting off my VPN access and disabling my e-mail account. I got a phone call from my manager informing me I was being laid off, indicating that I’d receive a package the next day via FedEx with documents to sign and return and with information on COBRA coverage, etc., and asking me to ship back the laptop and other company hardware I had.
My next company was acquired, a little less than a year after I rejoined them, by a bigger company. Obviously, some people were retained after the acquisition and some were not. On the day the deal closed, we were all told that we would be informed in a private meeting with our manager which group we were in. They scheduled the meetings so that all of those being retained were called in first – they basically told us “here’s your offer letter, hope you’ll stay, now take the rest of the day off and go home”. Once everyone they wanted to keep was out the door, they started in on those who weren’t being asked to stay. Most got severance in exchange for agreeing not to sue, and were escorted out after collecting their things. IT was standing by to terminate access as people left.
Six months later, they cut another group, using basically the same method – I was actually on the road when it happened, so I didn’t see it firsthand, but I did get a call from my manager early in the day letting me know that there were going to be layoffs that day but that I would not be affected.
I also witnessed a mass layoff recently at a customer – I was onsite working on a longterm project, and was there the day they implemented long-rumored layoffs. They basically told everyone in advance that the layoffs would happen on a particular day, and to expect to be available to meet with their manager. They called in the people who were being let go one at a time, then escorted them out. Then, about noon, they basically sent a broadcast message to everyone that they had completed all the staff reductions, and that if they hadn’t been called in they were not affected. Seemed like a pretty stressful way to handle it – not a lot of work got done that day.