Sharon037
Unfortunately there is no clear definition, however, you can reasonably reduce the figure to one day for the physical tests and the test must be performable for the majority of the time. So if you father can walk 100 mertres only two days a week, then for the majority of the time he cannot walk that distance.
It is also possible to argue that "reasonable regularity" applies, in as much that there is an expectation that the test should be repeatable within a reasonable period. If on the days that your father can walk, he can only do so once, then he should fail the test.
Now whilst these are reasonable conclusions to draw from the guidance and case law for the various benefits, ATOS's doctors, if relevant to your question, have a poor history of applying these criteria, forcing many claimants to go to appeal in order to receive their benefits.
Hope this helps
Stephen
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
