kristina, those questions have been asked for a long time now, and the answers are usually bound up in economics. There are many papers written on this subject, and here is one that you might find interesting.http://ndt.oxfordjournals.org/content/26/4/1128.fullIt's a bit long, so I'll just post the link. It is easy to read, though.
And we just love to be within our home surroundings rather than a group of chairs with people strapped down! Im glad that 3 days a week works for you, it just didnt for us! There are lots of people on IHD that still do In-Center! It is a matter of choice! We just love the home experience.God Bless,lmunchkin