Set it up once
Projects
A Project (in ChatGPT or Claude) is a workspace with its own instructions, uploaded files and conversation history. Make one per piece of ongoing work: a client, a report series, a team handbook. Every chat inside it starts with that context, so you stop re-explaining. On work plans, Projects can usually be shared with colleagues.
Gems and custom assistants
Gemini's Gems and similar features save a set of instructions as a named helper: "Proposal reviewer", "Meeting notes formatter". They suit repeatable jobs with a clear input and output. Write the instructions as you would for a new colleague: purpose, inputs, steps where order matters, and the format you want back.
Custom GPTs are retiring
OpenAI has scheduled custom GPTs to stop running on 11 December 2026, replaced by plugins shared between ChatGPT and Codex. Instructions and files migrate; custom actions, sharing settings and the chosen model do not. If your team relies on a GPT, inventory it, save its instructions, write a few test prompts, and migrate before the date. Check your own workspace notice, as dates can vary.
Keep them tidy
Reusable set-ups go stale: an old price list in a Project's files will be quoted confidently for months. Put a date in the instructions, review each set-up every quarter, and delete ones nobody uses. Don't upload anything to a shared Project that not everyone in it should see.
What instructions or background do you find yourself typing into an AI again and again?