Charging for value is a nice idea. How practical it is depends on a lot of things including how predictable the outcomes are and what the standard practice is. And, as your parable suggests, if you do bill by the hour/day, your rates are going to have to reflect (assuming you want to make a decent living and stay in the business) what percentage of your time can realistically be billable.
When I was doing IT advisory work for vendors, a fairly small percentage of my time was spent doing direct billable work for clients over and above annual subscriptions many of them paid us. The rest of the time was spent researching, being briefed by companies, talking to journalists, writing, etc. When we did do a specific project (for which we generally charged for a deliverable--although that deliverable could be a day of advisory work), we charged what would seem to most people a really high hourly rate because we had to capture all the non-billabel time (and, of course, because our rates were in line with industry norms for this type of work and companies apparently felt we delivered sufficient value to capture those rates).
By contrast, I did some legal work as well and for that was paid on an hourly basis at a much lower rate. But, because it was a big block of work and I could charge for any time related to the project--including travel, background reading, etc.--it was pretty good work.
When I was doing IT advisory work for vendors, a fairly small percentage of my time was spent doing direct billable work for clients over and above annual subscriptions many of them paid us. The rest of the time was spent researching, being briefed by companies, talking to journalists, writing, etc. When we did do a specific project (for which we generally charged for a deliverable--although that deliverable could be a day of advisory work), we charged what would seem to most people a really high hourly rate because we had to capture all the non-billabel time (and, of course, because our rates were in line with industry norms for this type of work and companies apparently felt we delivered sufficient value to capture those rates).
By contrast, I did some legal work as well and for that was paid on an hourly basis at a much lower rate. But, because it was a big block of work and I could charge for any time related to the project--including travel, background reading, etc.--it was pretty good work.