For perspective. WhenBART first was running M-F only and closing at 8PM, they had corrosion based issuesbetween wheels and rails. IINM, they installed scrapers on the wheels.
Bonus weirdness: SLACK the Stanford linear accelerator found that after Fri evening shutdown of the third rail energy, they had to recalibrate even though they were miles from any BART tracks. Mondays when the tracks went live again, another recalibration.