I totally agree with Rananim that flying skills have to be practised to maintain a level of competency, but I still maintain that ultra busy TMA's like LHR and ORD are the wrong venues for practise. Why pile on the workload when you should be keeping a close eye on conflicting traffic and the safe profile of the aircraft? It goes double for busy American fields like ORD, LAX,JFK and SFO, where runway changes seem to happen at the last minute, and controllers often make no allowance for track miles to run to touchdown when giving clearances, putting the onus on the pilot to comply or go around .