Here is how I understand family size (with the caveat that among Christians who have given no indication to the contrary, I am so mired in my own reality as to consider non-contraception to be the default practice. Terribly naive of me, I know, though I mean for it to be charitable):
1=small (may indicate fertility problems)
2=Normal! Way to go!
3=trying for a boy or girl, or a "mistake"
4-5=bigger than normal (indicates mild or moderate parental zaniness, or twins)
But six is where it gets serious. Six kids doesn't happen by accident. Six kids is beyond zany. Six is full-on crazy. Six kids very likely means a weird vehicle. Six is Big.
Six is also where some people (not all) seem to begin considering themselves major parenting experts and get real annoying. I promise I'll try not to do that. (It would be hard to come off as a parenting expert when my oldest kid is eight, anyway--lots of critical stages still not even touched.)
I think six will have some advantages, though. No odd box of raisins left to fossilize in the cabinet. That's been a huge problem with five.