Al and I are building a bathroom vanity, and a closet door for his Sister in law, and her wife. We've built many things for them in the past, including a full kitchen remodel. This vanity will be a modern, White Oak, 60" unit. Center mounted single sink, and three drawers on each side.
If you've ever had to squeeze into a 14" opening to install drawer glides, you will have learned to measure and install them prior to assembling the cabinet. So that's just what we did today.
Not too much head scratching, before figuring out the correct placements.
Those are the interior dividers. The side pieces were done before these.