It happens a lot - esp when INT N and S are bandboxed so no co-ordination is needed.
Can happen for a load of reasons as Gonzo said - sometimes there is a go-around/emergency and extra track mileage is needed for the following aircraft. The aircraft may be next in sequence close behind one below and need a few extra miles (and a spin at the hold would put them too far behind) - and then there are lots of survey flights around.
Lots of reasons - some ATCO's just like using a bit if flair and the whole RMA to avoid the monotomy!!
Where's HD when you need him....?
