Please, know that is only my way of tracking fabric in and out at this time in my quilting life. I keep a medium sized spiral bound notebook where I journal my quilts made, progress and fabric in and out month by month. It took a few years to figure out a reasonable plan/format that works for me that was not too hard to keep up with. I have been doing it for 5 or 6 years. I just want to leave a legacy of information about my quilt journey.
Fabric OUT is generally a good calculated estimate. Calculate square inches in a finished project times two (front and back) Then I divide it by 1440 (approx. square inches in a yard) and Ta-Da I have the amount of yardage I have used. I don't worry about the amount of fabric in seams and so on. Fabric IN is simple because now I only purchase yardage when I need it for a specific project or backing. (I seldom take advantage of my guild's give away table. I just don't need it.
Track or not track, but if you track, do it in a way the fits YOU and what you want to track.