In terms of “should have been far less time consuming” rather that just “time consuming”: Unspecified functionality/design: My clients are often non-technical

In terms of “should have been far less time consuming” rather that just “time consuming”: Unspecified functionality/design: My clients are often non-technical (not developers) and UI/graphic designers. So there can easily be a lack of understanding and rigorous communication if you don’t take the time to write things down and keep an updated version of that thing as you figure out the unknowns.