There are significant limitations to bulk updating properties in Notion. Here are a few techniques.
Personally I use database automations the most, combined with automation formulas for setting the values based on more complex logic.
a. Open the database in full screen.
b. Apply a filter if you want to limit the changes.
c. Keep scrolling until you reach ~1000 pages, then select all.
d. Make the change.
e. Repeat until all changes are made.
a. Create a button automation that edits pages in a database.
b. If there are more than 1000 pages to change, add a filter that limits to < 1000 pages.
c. Press the button!
d. Update the filter so another 1000 (or the remaining) will be updated.
e. Press the button!
f. Repeat until done.
a. Create a database automation on adding a page updates pages in the database.
b. Add a filter so it ignores pages that have already been updated.
c. Add a dummy page that you can find later (e.g. name “delete me”)
d. Wait for and confirm the automation has run. It will do about ~1000 at a time.
e. Repeat c-d until all have been added.
f. Remove the automation and delete the dummy ‘delete me’ pages.