Sure, probably. I worked briefly for a small (2-5 engineer, plus designers, and administrative) consultancy that did web app development; we had multiple client

Sure, probably. I worked briefly for a small (2-5 engineer, plus designers, and administrative) consultancy that did web app development; we had multiple clients at once, some clients got two FTE days a week of our time or less, sure. So I don't see why it shouldn't be possible. (Whether you can charge enough to live off of 2 days a week of work, I don't know, and depends on your living standard and location!) But there's a lot of work that isn't your hourly billable that goes into running such a business too, administrative overhead, client relationship management/development, etc. I personally ultimately decided this kind of consultancy was not work I found rewarding. I also was not one of the owners/principals, and was not there very long, so I'm not really an expert in this kind of business, and probably there are people who might be better to give you advice. But since you asked.