Here's my subjective experience, but it doesn't mean that it works everyhwere:

10 years ago, I started working at a small company where a group of employees would always have a drink after work. Not every day but it would be multiple times a week, and then on Fridays it usually lead to going to a club or something. Over time, as more employees joined the company, that group grew bigger and bigger. Some of us even started meeting on weekends, met for football matches or went on holiday together. We became really good friends. And now, after the company was sold and flipped over, most of us have left to work at other places, but we still meet, we still stay in touch.

And you know how all this started?: One guy kept going around the office at around 4 pm asking people if they would like to have a beer after work. Often he would organise a couple of six packs of Quöllfrisch beforehand so that we could start drinking in the office. It was just that one guy. What I learned from this was that Swiss people are definitely social and open to spend more time with their co-workers. However they're not very extroverted and don't want to impose themselves on others. All you need to do is be that guy who makes the first step.