One thing I like about 5e is that higher level characters do not necessarily become "untouchable", and as a result, it's more feasible to have interactions between characters of different levels (and some people talked about this with regards to sandbox style gaming). So suppose I am DMing a group of 3 lvl 1 PCs that are traveling with a CR 5 NPC, as if they are apprentices learning the ropes. How should I be dividing an encounter that is worth 1000 xp? Should it be even distribution (each gets 250 xp) or should the CR 5 NPC weigh more (and if so, how much more?)?