Shouldn't "We walk in circles" be accepted too as a more English way to put it?
EDIT: This used to be me being wrong. Sorry.
I see what you mean, but I suppose there is a literal sense to it keeping the noun plural or singular in translation.
So this sentence talks about literal walking, in an actual circle? Which expression would you choose for a metaphorical sense?
So, in Swedish you can say either "i cirklar" or "i en cirkel"? Okay then :)
Yep, I would say so.
When using, "i en cirkel", you could also say "vi har gått i en cirkel" (we have walked in a circle). If you were to suddenly realize that you've been walking in a circle (you find yourself in the place where you started), you would likely say that.