I use it for boilerplate content, contact info, etc. email addresses, phone numbers, etc. but when I build sites for others, they rarely understand that if you change it here, it is changed everywhere.

I vote for ‘Synced Content’ – to emphasise the content is synced across the site, not just the style of the block.

Plus, the prompt for saving the block should be changed from: “are you ready to save the following blocks” to: “are you ready to sync…”