Self-performed labor is usually the riskiest line in a job budget, and the wage on the timecard understates it. Labor burden is everything on top of the wage that you pay because the person works for you: employer payroll taxes (Social Security and Medicare, plus federal and state unemployment, which apply only up to wage caps), workers' compensation premiums, general liability charged on payroll, health and other benefits, union fringes where they apply, and paid time off.
Paid time off and other unbillable hours matter twice: you pay for those hours, and they are not available to be charged to jobs. So the honest number is cost per productive hour, not per paid hour.
Workers' comp rates vary widely by trade classification, state and your own experience modifier, so a burden number borrowed from another contractor or another trade can be badly wrong. The right move is to calculate your own, by class, and update it when rates change.
If your estimates and your job cost reports use different labor rates, the job will look like it is fading when it was simply bid on the wrong number. Use the same burdened rate in both.