My 5 (so far) redundancy experiences have all been at the hands of Canadian and US company takeovers of the company I worked for. Some of them paid out a reasonable 1 month per year served redundancy, some paid the legal minimum, one tried to pay some people 1 month/year and others the legal minimum, got sued and lost.
No matter what they did, they invariably lost good staff as the second they announced the redundancies, people started looking elsewhere and some jumped ship before the redundancy, often the people they wanted to keep.
My experience of these redundancies is that there seems to be a knee jerk reflex after taking over a company where they make 1/3 of the staff redundant, lose another 1/6 to people jumping ship, and then spend the next 4 years hiring and training people up to get back to where they were when they bought the company. In one instance the company I was working for got bought because we were thrashing them in the market so we got bought to stifle competition. Didn't work as those that left just setup again and within a year they were again thrashing them.
Finally, a friend of mine got laid off when his company shut down his department. No biggie, he got 12 months redundancy and found a new job starting the day after he finished for more money. 2 weeks after he finished, he got a call asking if he could come back on contract. Turns out they laid off 4 people who were vital to a contract that they hadn't fulfilled, and he was one of the 4. He ended up going back under contract from his new employers who paid him £2k per day for over 6 months. He asked his new employers how much more than the £2k they were charging his former employers and they just laughed and wouldn't say. He paid off his mortgage in those 6 months and never looked back.