Accounts that keep going for years are not run by people with more ideas. They are run by people with a routine, and the routine is short enough to survive a bad week.
One: plan the month, not the day
Pick three or four subjects the account is about and give each a slot in the week. A Tuesday that is always the craft post is a Tuesday that never starts from a blank page.
Two: make in batches
Photos, captions and edits all go faster in a run than one at a time. An afternoon of shooting and an hour of writing covers a fortnight — and the posts come out of one mood rather than fourteen.
Three: schedule and walk away
Put the batch on the calendar at the minutes your audience is actually there, and let the worker publish. Posting by hand at 7pm every day is the step most people quit on, so remove it.
Four: look back once a week
Ten minutes. Which post did people save, which did they forward, which slot went quiet. Adjust one thing for next week — the slot, the subject, the format — and only one, so you know what did it.
The failure mode is skipping step four. Without it the loop still runs, but it runs the same week forever.