How to structure GPT for journalling

I am building a journalling GPT.
Each day a user will share his/hers thoughts with it, describe how was the day, etc. It should be easy to enter such dairy entries.
Sometimes, the user will ask GPT to give some insights and ideas based on previous dairy entries. Also users can ask for example to help write articles based on the users’ previously entered thoughts for a long period.
I am not sure what is the best way to structure and use this:
Should a user have one, long chat for everything?
Or the user will enter all the diary entries in one chat, but in another, separate chat the user will ask it to help write articles based on the first diary chat?
Or maybe, for each day the user will open a separate chat, and then, will create separate chats for weekly summary, ideas for articles etc.
I am not sure can a Custom GPT refer from one chat to other chats in the same GPT?
Would appreciate any advice
Thanks