My experience is funnily enough the opposite. When on fixed-price, it was always an argument about if something was a bug (thus I had to fix for free), ambiguou

My experience is funnily enough the opposite. When on fixed-price, it was always an argument about if something was a bug (thus I had to fix for free), ambiguously specified or a change from original requirements (they would have to pay to change for the last two). I felt we always were adversary to each other. With an hourly contract, we're on the same team and try to use me for the most valuable stuff as long as you have me.