It is to increase those wishing to attend and can get away for an evening.

For travelling ladies at least. I've had to miss some because they are on Wednesdays. Unfortunately, weekends are tough for folks with families.

Steph xoxo

The last few in NY have been on Wednesdays.  In the past, when someone else was hosting them they tended to be on Thursdays.  I think the hosts pick a night that's good for them (obviously) and then, if it works out well, they stick with that night.

Personally, I wouldn't mind if they mixed it up.  Some people have regular commitments.  There are probably people who can never attend on a Wednesday.  Likewise, there are some who could never attend on a Thursday.  So, by varying the night you open it up to make it more accessible to more people.  But, there is also something to be said for sticking with what works and keeping it on a the same night that your regulars can come.