Re: atmosphere, I recall reading studies that a certain proportion of people who are both exceptionally good
and widely recognized by management as such, and therefore in no real risk of being chosen in a layoff round, nonetheless get very jittery during layoffs, fearing that they'll be next. Iirc two contributors are that some skilled employees massively underrate their own performance, and others just don't trust the layoff-selection process, treating it as an unpredictable and possibly random adversary.
There's also not much room for error, because if people who are considered good by peers get laid off, trust in management's judgment takes a nose-dive. I remember my dad and his coworkers kind of holding one layoff against management for years, when a highly regarded member of the group was laid off. They were so incredulous people would use it as a running joke, "yeah, but remember these are the geniuses who fired [guy]".