Has gog changed something? The tradition has been the team releases games on tuesday, and has sales on Friday. I think baldurs gate was an exception to the rule due to the relaunch. Sorry for the attempt at bursting your balloon.
No, before this summer, it was usual to have one game on Tuesday and one on Thursday.
(And in the begginning, Tuesday was release-day, with two games per Tuesday.)
No, it was occasionally like that, but the not-so-hard-and-fast rule has always been new releases on Tuesday, news and coming soon announcements on Thursdays and sales on Fridays. When they have something special or a surprise release, it might happen on a Thursday, but that has still never been a regular release day.