The point about easterlies is that the departure runway maybe used for landing purely subject to traffic whereas on westerlies special procedures apply.
OK, I'm with you now - you're talking about what happens after 0700, when segregated operations start.
Westerly landings on the departure runway (i.e. out-of-alternation) are allowed where severe inbound congestion occurs, or is anticipated to occur, involving delays of 20 minutes or more.
Easterly landings on the departure runway are purely at the discretion of ATC, are not subject to the above delay criteria, and are not considered as out-of-alternation since there is no alternation (yet) on easterlies.