This occured on Test Wikipedia — https://test.wikipedia.org/wiki/Special:Block/Nov-1-2018-test — on November 1, 2018. I didn't test for blocks of 9, 8, 7, or 6 pages but I imagine they are also time consuming.
This video shows 4 work flows: https://drive.google.com/open?id=1Msu6Hvgc3X7yEg-DkuXMItIlGbBnwGry
------
**Use case 1: Setting a large partial block**
0:00 – Start setting partial block with 10 pages for user with no current block
0:18 — Click “block this user”
0:19 — “Block succeeded” displays
OUTCOME: ✅ Success, acceptable user experience.
PROCESSING TIME: 1 second
------
**Use case 2: Modifying a large partial block, adding and removing**
00:26 — begin modifying block to remove one page from 10 and add an alternate
00:35 — click “re-block the user with these settings”
1:29 — “Database error” page displays
OUTCOME: ❌ Failure, unacceptable user experience
PROCESSING TIME: 54 seconds
------
**Use case 3: Modifying a large partial block, removing**
1:40 — begin modifying block to remove one page from 10
1:45 — click “re-block the user with these settings”
2:38 — “block succeeded” displays
OUTCOME: ❌ Success, but unacceptable user experience
PROCESSING TIME: 53 seconds
------
**Use case 3: Modifying a large partial block, adding**
2:48 — begin modifying block to add one page to 9
2:54 — click “re-block the user with these settings”
2:59 — “block succeeded” displays
OUTCOME: ✅ Success, acceptable user experience.
PROCESSING TIME: 5 seconds