I think in most cases yes, but some I come across the sheer weight of traffic on the roundabout (at peak times mainly) means that no traffic would be able to join (say at a junction immediately prior to a major one which has 99% of traffic on the roundabout passing it and making the traffic waiting, keep waiting)
Which leads back to: Why is there a roundabout in the first place?
Huuuge roundabouts with traffic lights should really be good old-fashioned crossroads. Those take less space and work fine. Roundabouts tend to be a better solution _if you don't have the constant flow of heavy traffic_.
I agree with the gp: Either a roundabout xor traffic lights.
