For 2Ps/1Ps, I think it's best to use the e500s as much as possible. Before I adopted this approach, those things were expiring all the time because they don't always clear for the big flights I save them for. (Though this year as 2P, I'm 3/3 using them for transcon bos<=>sfo/lax. Way better than expiring! Need to start the "upgrades getting easier" thread.)