Weekend commits are actually less likely to introduce vulnerabilities, but they take 45% longer to fix.
I can only think of contributors being nice and relaxed, doing their most brilliant work. Work that is a bit too brilliant for the same contributor to fix any bugs found during any other conditions.
insert that one quote about being too smart for one's own good
Edit: Weekend commits are 8% less likely to have bugs, but those bugs take 45% longer to fix! This site is gold.
Edit 2: that may not mean what it looks like at first blush.

