What you are seeing is a break in grids. For 1:24k contours the USGS determined the appropriate interval in a 7.5 minute grid (I believe). At the line the contour interval can change.
If you want perfect contours you can download the DEM elevation raw data and generate your own. At that point you'll pick one contour interval for the entire state. The old maps/old tutorial (the data is still there) did it that way; with the contour lines available I choose to accept the "ending of lines" to have a varying contour interval across the state.
If you want perfect contours you can download the DEM elevation raw data and generate your own. At that point you'll pick one contour interval for the entire state. The old maps/old tutorial (the data is still there) did it that way; with the contour lines available I choose to accept the "ending of lines" to have a varying contour interval across the state.