Switzerland is in Schengen and they kept border checks all the time, also strict limits on goods transferred etc.
Not sure "all the time" is accurate. Two years ago I drove a car through Switzerland, entering from the South border and leaving at the North border (and ~3 weeks later, the opposite way), there was no border checks at all. The only control we encountered when traveling from Spain to Sweden (and vice-versa) by car was the quick checks at the German<>Denmark ferry border.
Yes, of course, but this is true anywhere, not just for the places under the "Temporary Reintroduction of Border Control".
But all major are and were in the past, all frontaliers coming daily for the jobs in all border cantons can tell you about wonders of morning checks corresponding massive traffic jams forming in front of the border crossings, every single day. 1/3 of my office colleagues experience this every day.
Major eastern border crossings are 100% manned though, morning day night doesn't matter.
They do not check extra hard, though... It's been a number of years but they used to wave cars through or even have border/customs checkpoints closed depending on their 'mood'...