I'm getting the sense that Disco S3 pacing is somewhat similar to Picard S1.
Episodes 1-5 are Act I
Episodes 6-10 will be Act II
Episodes 11-13 will be Act III
That's the sense I'm getting out of it.
Picard Season 1 also followed a three-act structure (Eps 1-3, 4-8, and 9-10). It's understandable that DSC S3's first act is longer than PIC S1's.
When
Picard was introducing us to the eve of a new century, it was more like the odometer was about to roll over from "99" to "00". A new century just happened to come up. And we had 21 seasons of the 24th Century and four films to pick up from.
In
Discovery's third season, they have to introduce us to something totally new that we hadn't ever seen before, except for possibly "Calypso". So the first episode introduces Burnham to the 32nd Century. Then a year passes, so she can get used to the time. Then in the second episode, Discovery appears and they get introduced to the 32nd Century. Then the third episode, Burnham and Discovery are reunited and the first thing they do is go to Earth. Where we find out Earth's not part of the Federation anymore. Then Adira comes along. Then, in the fourth episode, Adira helps them find out where the Federation is. Then comes the fifth episode and we finally see the Federation and it takes the entire episode for Starfleet to accept Discovery and for Discovery to become part of the fleet again.
For those who don't want to read the above paragraph (who wants to read a big block of text?

), let's just say I'm glad we had five episodes' worth of transition. It's needed when you shift things so radically.