How do you protect truly sensitive information when “encryption alone” isn’t enough?

I’m curious how people protect truly sensitive info when the real risk isn’t “AES gets broken,” but “it leaks during sharing, coordination, or human error” over everyday channels (chat/email/cloud links).

Two examples:

• Example A (friend, anonymized):
  My friend shared a dissertation draft (epilepsy-medication research) via a folder link for quick feedback, planning to secure it later. The link got forwarded, permissions were too open, and the draft leaked. No hacking — just human error + link forwarding.

• Example B (real, last 2 years):
  In Aug 2025, ICE accidentally added a random person to a group text (“Mass Text”), exposing sensitive operational details in real time. It wasn’t a sophisticated breach — it was a simple “wrong recipient added to the thread” mistake, but with serious consequences.

I’m asking because I’m a developer and I’m currently prototyping an offline-first approach to “send now, reveal later” file sharing, where access can be conditional — not just “who has the link,” but also when and where it becomes readable.

Main question (please share your workflow):

When you have to send sensitive data over open channels (chat/email/drive links), what’s your practical workflow to keep it safe and prevent premature / accidental access?

If you’re willing, please share your own methods (or even better: your “do’s and don’ts”) — especially workflows that normal users can realistically follow.

Also: Do you know any tools/workflows that support more “conditional” access — e.g., a file that becomes readable only at a specific time (at noon, next week, in a month) or only in a specific place (a city, neighborhood, street, park)?