I’m a writer and I work, almost exclusively, on a value basis: we agree a price and I deliver.
Charging by the hour/day or, worse, per word is a killer for both quality and trust.
However, I’ve always kept timesheets for my own analysis, so that I can see how much those value-based projects actually cost me in bloody, sweaty, teary hours. They used to be simple Excel spreadsheets, one for every project, so I could work out the actual cost per hour arising from either my poor estimating or delightful rat-holing. But, I always knew that created hidden gaps.
Give your heart to the trade you have learnt, and draw refreshment from it. Let the rest of your days be spent as one who has wholeheartedly committed his all to the gods, and is thenceforth no man’s master or slave.