No it doesn't. You get 6 allowances. You can only split up until one or both reach rank 2. After that, you get 6 quests per tribe so you can't split up without slowing down. I sort of see what you're saying (b/c you can do all 7 rep quests instead of 3 7 and 3 5) but if you want one tribe's reward sooner then you should do only that tribe's quests.
