I'll jump in with my account and say that I, too, received both an email congratulating on my original take and another updating me about my higher retake scores - both well after they had originally been updated on the site.
For reference, I received my new online GMAT score within 48 hours of my sitting. (750 - Q49 V44 IR8 ...not my best performance, but I'll live with it, considering I ended up rescheduling to a pre-5am sitting after waiting at the launch screen for an hour and a half and then receiving an error message that I would not be able to test at my originally scheduled time. That said, if you're willing to sit on hold with the chat for long enough (or reach out to your region-specific phone line), it does seem that they can expedite the reschedule process if the error was on their end and prior to the start of the exam.)
I also sat for the EA a few days earlier (170, IR18 V14 Q18) and received those scores in a little over 24 hours. So, a few takeaways on the experience standpoint:
1) If you're in a time-crunch and do encounter tech issues, reaching out to the chat/phone line and explaining the error may get you re-situated faster than waiting for them to begin and process a case. (...but expect to *wait* a while!)
2) Scores seem to be getting posted fairly quickly to the site (for myself and for my students at least), but are not always accompanied by an email update. (I didn't receive one at all for my GMAT/EA online scores up until this apparent glitch.)
3) While some scores may be taking longer to post (I'm assuming based on the review processes and, as others have mentioned, the potential that certain activities might have been flagged for review) the delay in receiving scores does not seem to depend at all on score level (at least from the score performances I've seen in my retest and the results of my students).
I hope this helps!
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Hailey Cusimano
GMAT Tutor and Instructor