Well, I would imagine there are work arounds or ways to make good estimations, but just ignore it for now and move on. Even reading about why its good to know the hourly wage can be inspirational in itself.
My favourite tip from the book other than the charts and calculations is about anticipating need so you can look out for good deals, rather than panic buy and thinking outside the box. Its really simple but I hadnt really given much though. Mysupermarket.com now has a "savvy buys" section which tracks prices and can send alerts. So, lets say you only buy Plenty kitchen roll, but rather than wait til you run out, you track the price and buy a pack or two based on your needs, when it goes on sale. A lot of things go on sale on a regular basis.... but now Im getting onto money saving rather than decluttering! (Actually, I tend to hoard long life food and cleaning products, but its not a major issue)
As I look around my house I see that a lot of stuff is "aspirational clutter" - the paint that I bought 2 or 3 years ago to paint the hall / stairs / landing, the stuff for my bedroom, plus the craft projects Ive purchased for but never had the time.
So, my thoughts have lead me to re-instating my craft room (currently full of ebay stuff) but will include all the other projects (the wall paint etc) and make a list of all the projects I already have supplies for. Ill store the list somewhere prominent to remind me the next time I decide that a project looks fun I DONT NEED ANOTHER PROJECT! I might eventually let go of some if it, but ill work on rest of house first.
Plus when all that clutter is contained, I can see what is left and what really needs addressed.