in Hamburg's swimmer's lanes it's obligate to swim "circles", but we swim counter clockwise...
In the SCM pool there's only a single lane and you can forget continues swims if more than four swimmers in.
In the LCM pool there are doubled laps and it's possible to swim relatively continues for up to 10-12 swimmers. Exact pauses to fit in again are the major Problem here. Public, "Tempo" swimmers and BS have their own doubled lanes.
I've once swam in a SCM in Düsseldorf there were two laps for swimmers with cable in the middle where we could swim around as (short) cable swimming in USA. (Also counter clockWise, so clockwise swimming might be a Scottish specialty...)