The other week, I agreed to copy edit a manuscript for someone.
When asked for a cost estimate, I used my past experience proofing book manuscripts to figure out how long it would take me to get through a 90-page manuscript. Then, I took that number and multiplied it by my hourly rate.
Three and a half hours into the project, it became clear to me that I had drastically miscalculated. The project could actually cost up to three times more than I had previously projected.
I was mortified.