Hi there, citychik, nice to meet you.
I have definitely heard of the solution of 3 moderate cleaning days to take the place of one heavy, one light. I think I've heard mostly good things about it - don't remember any problem coming up. So I think that's smart and definitely recommend it - I would like to hear how it works out for you.
Like you, I have to adapt to a changeable lifestyle, but also like you, I want to firm up what I'm going to do each day. So I understand how you want to have a good concept of the days/plan.
In my opinion, time left available within the Basic Weekly Plan automatically becomes project time. That's one point of P and P's vision, I think - become organized to create time so that you can become and do what you desire. So you can get to the projects you've been dreaming of. And project time depends upon priorities you set that week. If you plan, and then realize that you've provided plenty of free time to share for the two of you yet have extra, then I would plug in project time, either couple-projects or your own.
P and P suggested that we think of 5 reasons why we want to be organized and 10 things we love to do. These were to be our inspiration for our efforts. So then, every time we get to work on one of those dreams, we can know our basic weekly plan has been a success.
For instance, for me, that might include things as varied as creative time for sewing, a photo-organizing effort, home repair, long-neglected attention to wardrobe, visiting extended family.
I used to have time for projects every weekday - usually about 2 hours midday. That worked out beautifully. Right now, I put in a great deal of eldercare time, so it hasn't worked out, but I'm trying to tweak my plans so that I can get back to it.