I don't pay attention to hours at all. Strictly look at gross profit per day, or per week, depending on the type of work.
After a year or two, it's pretty easy to figure your annual overhead, and divide it by 50 weeks, and 5 days a week to get your overhead per workday. Add your desired wage per day, and that's the minimum gross profit you need to achieve, per day. Gross profit's pretty easy - take your finished sale price, subtract COGS, subtract shipping cost etc, and there you are.
There are some days where I might complete 4 or 5 orders, start to finish, because they are little items. For those days, you can usually compare your gross profit to your daily gross profit minimum, to see how you are doing. In reality, lots of orders will carry over into multiple days, or you'll have a day where you are pretty much chasing around a billion little things, and can barely get your hands on the tools. If all goes to plan, those days are followed by a day or two of completely knocking it out of the park, because everything is setup and ready. For that reason, I usually look at the week as a whole.
The nice thing about that is if I work a day on the weekend, or stay real late, (or better yet, take a day off), I don't have to reevaluate what the overhead should be - just take completed work that week, subtract 5 days worth of overhead, and that's all she wrote.