There are two aspects to learning Air Law:
(1) Stuff that it's useful to know from the point of view of staying alive and out of trouble (rights of way, rules of the air, weather minima, controlled airspace, that sort of thing).
(2) Stuff that is totally irrelevant that you can forget the second you've passed the exam (what colour paper some 1932 treaty was printed on, rules applicable only above 250 knots and 10,000', that sort of thing).
Your primary objective is to learn (1) properly so that you can in future use it to stay alive and out of trouble. Your secondary objective is to memorise (2) temporarily, just sufficiently and for just long enough to pass the exam. Depending on how your brain works you may wish to apply different study techniques to the two classes of information, such as getting (1) into your long term memory properly but cribbing up (2) on the morning of the exam.
(In practice even some of the (1) information is pretty useless in terms of day to day practical implications for the PPL holder. Who cares whether the minimum legal visibility for a particular purpose is 1500m or 1800m or 3km or 5km if you fly for fun and would never take off with less than 8km because that isn't fun?)