Your question is too broad to be answerable. There are so many variables that at different times any one of any of the things mentioned - and more - can be more, or less, of a limit than the others. Depends on the day: weather, traffic, particular aircraft qualities, airfield qualities/equipment/navaids/type of approach,single/multi crew, overall experience, particular experience in similar or same circumstances, other crew experience, recent experience, unserviceabilities, etc etc.
Some of the categories of tasks you've used encompass some of the others eg 'flight management' vs the other tasks you've mentioned. I understand 'flight management' to be all factors that relate to one's conduct of the flight including the choice of information sources, assignment of attention priorities, decisiions based on these things, execution of these decisions & finally a review process to determine outcomes & response.
Last edited by Tinstaafl; 2nd December 2003 at 08:04.