How I learned to become a failure
medium.com
medium.com
Of course, adapting this model puts more risk on you as the designer - however, if you get good at it, you can finish projects in a much smaller time frame and technically skyrocket your "hourly" rate.
This is how I would always approach clients - 1 price to get want you want, fuck ups are on me. And the reason I would word it like that is for one very PRIME reason:
Most clients don't understand the value of the iterative failure.
Yep, except when you're a consultant/contractor/freelance. You can certainly spend the time, just don't expect to be compensated for it.
And therein lies the rub -- anyone willing to allow a designer to work in such a manner cares about design, and quite often isn't interested in outsourcing that to the lone-wolf. They may do that with a firm, or have their own in-house talent, but rare is the situation where a client is willing to accommodate perpetual iteration from a contractor while burning hours.
*edit for a sloppy typo
They want to see change as it happens, and eventually have that 'aha' moment where they realize they'd never have gotten from here to there if they hadn't gone through the middle part.