Do Admissions portals ever update on the weekend?

As noted above, some schools do release decisions on weekends. Note that some schools also announce in advance when they are going to release decisions - almost all of the schools my son applied to did this, although in a couple of cases, he heard ahead of the regular deadline. It’s worth checking the schools’ Social Media feeds to see if they provide this kind of information. You can also sometimes get a good idea by looking at the CC threads for specific schools from last year.