I have a quilt journal, and I definitely put start and finish dates in. I don't see any of my quilts as a "race to finish", and think the longer something takes usually means it's a lot more complicated. I also put size, reason it was made, and tips or hints I learned along the way.
But reading a book in the library the other day and there was a fabric journal from the 1900s. A woman had added small patches of each fabric she used, often cut out into cute little animal shapes, and glued them into her journal. I thought that was a really good idea, especially since my digital photos never seem to accurately capture the colours.