These closings will give Metro 8 to 8½ more hours a week when the system is closed, which will allow for more track work. It's certainly true Metro needs to catch up on track work, and single-tracking constrains workers too much so they can't get as much done.
Beyond the urgent safety-related fixes, Metro could use track time to fix lighting in stations (which requires closing the stations), installing cables for cell phone access in the tunnels, and much more, said General Manager Paul Wiedefeld when a few Greater Greater Washington contributors and I spoke with him recently.
However, what this proposal does not explain is why closing the entire system at once is necessary. Why not, for instance, pick one line per weekend to close at night? Heck, if they need more track time, it might even be fine to close a line for the entire weekend.