Beersmith batch sparge question???

Okay, so if my initial infusion for 8.0lbs of grain is 10.0qts and my 2 saprge volumes are 2.21gal, and 3.75gal, I am assuming that Beersmith is calculating that I am collecting my first runnigs without adding any sparge water, right?

If so, why wouldn't I just do two equal sparge volumes of 3gal respectively to simplify the 2nd and 3rd runnings, am I missing something?

You are correct in your first question. Regarding equal sparge volumes you can set up brewsmith to do just that (sparge using equal volumes), it's just not the default option.

Okay, another question, under "mash profile" the section with "batch sparge" options, what exactly is it asking for when it says batch sparge using batches that fill ___% of the mash tun volume?

It is usually 90-100% of the mash tun volume, but I have a 13 gallon mash tun, if I am only making a 5 gallon batch why is defauting 90-100% of the mash tun volume when there is going to be a significantly smaller mash volume?

I am a little confused by it.