When you crunch the numbers, Congress looks pretty lazy. The Washington Post finds that both chambers have been in session only about 40% of the time since 1978—the first year for which online records are available—and they've both worked full weeks simultaneously a measly 14% of the time. Taken individually, the Senate has spent 42% of the past 37 years in session, while the House has been in session 39% of the time.
That period covers 1,917 weeks, 601 of which the Senate worked Monday through Friday. As for the House? Just 362 weeks. This year so far, both chambers have been in session all week together … four times. They tend to avoid working on Fridays, Philip Bump notes. Meanwhile, the longest period both chambers remained in session was 13 days, while the longest time neither chamber worked was "several months," Bump writes. But he does point out that just because Congresspeople aren't meeting on the floor doesn't necessarily mean they're not working. See the graphs and check individual dates here.