If they say that they do deploy on Fridays, I ask whether they do multiple deploys a day as a routine. Some SRE orgs have their gears oiled so well that deploying stuff is trivial, and rolling stuff back is also trivial (and may even be automatic). If so, I'm glad and continue with the interviewing process.
If the answer is "yes, when the deadlines are tight", then I cancel further interviews. This means inevitable and regular overtime on weekends (because deadlines are always tight), and I need my weekends for my family.
That would mean that their deploy/release procedure is so brittle that they have frequent outages/problems or expect deploys/releases to introduce issues, so they avoid deploying on Fridays so no one has to work during the weekend.
